Silver-containing precursor and product articles containing cellulosic polymers

ABSTRACT

An article has a substrate and a pattern of a dry silver nanoparticle-containing composition comprising at least 20 weight % of one or more (a) polymers, that are cellulosic polymers; (d) silver nanoparticles having a mean particle size of 25-750 nm and present in an amount of 0.1-400 weight %, based on the total weight of the one or more (a) polymers; and (e) carbon black in an amount of 5-50 weight %, based on the total weight of the one or more (a) polymers. Such patterns can have multiple fine lines of any geometric arrangement. The article can have multiple patterns of this type, and each pattern can be electrolessly plated with a suitable metal such as copper to provide electrically-conductive product articles.

RELATED APPLICATIONS

Reference is made to the following commonly assigned patentapplications, the disclosures of all of which are incorporated herein byreference:

U.S. Ser. No. 15/456,686 (filed on Mar. 13, 2017, by Shukla and Donovan)and entitled “Method of Forming Silver Nanoparticles Using CellulosicPolymers” now abandoned; and

U.S. Ser. No. 15/456,827 (filed on Mar. 13, 2017, by Shukla, Donovan,and Gillmor) and entitled “Silver-containing Compositions ContainingCellulosic Polymers,” now granted as U.S. Pat. No. 10,214,657.

FIELD OF THE INVENTION

This invention relates to a Precursor articles containing one or morepatterns containing silver nanoparticles mixed with cellulosic polymersand carbon black on a suitable substrate. The silver nanoparticles canbe used as seed metal catalysts to form multiple electrolessly platedelectrically-conductive metal patterns in product articles.

BACKGROUND OF THE INVENTION

It is well known that silver has desirable electrical and thermalconductivity, catalytic properties, and antimicrobial behavior. Thus,silver and silver-containing compounds have been widely used in alloys,metal plating processes, electronic devices, imaging sciences, medicine,clothing or other fibrous materials, and other commercial and industrialarticles and processes to take advantage of silver's beneficialproperties.

For example, silver compounds or silver metal have been described foruse as metallic patterns or electrodes in metal wiring patterns, printedcircuit boards (PCB's), flexible printed circuit boards (FPC's),antennas for radio frequency identification (RFID) tags, plasma displaypanels (PDP's), liquid crystal displays (LCD's), organic light emittingdiodes (OLED's), flexible displays, and organic thin film transistors(OTFT's), among other electronic devices known in the art.

Rapid advances are also occurring for making and using variouselectronic devices for communication, financial, and archival purposes.

Silver is an ideal conductor having electrical conductivity 50 to 100times greater than indium tin oxide that is commonly used today in manydevices. For example, the art has described the preparation ofelectrically-conductive films by forming and developing (reducing) asilver halide image in “photographic” silver halide emulsions through anappropriate mask to form electrically-conductive grid networks havingsilver wires having average sizes (width and height) of less than 10 μmand having appropriate lengths.

While silver as an electrical conductor has a wide range of potentialuses in the field of printed electronics, the microfabrication ofelectrically-conductive tracks (grids, wires, or patterns) byphotolithographic and electroless techniques is time consuming andexpensive, and there is an industrial need for direct digital printingto simplify the processes and to reduce manufacturing costs.

Furthermore, it is desirable to fabricate silver-containing electronicsonto polymeric or similar temperature-sensitive substrates bysolution-based printing processes. Metallic electrically-conductivewires or grids of low resistance must be achieved at sufficiently lowtemperatures so as to be compatible with organic electronics onpolymeric substrates. Among various known methods for fabricatingelectrically-conductive silver grids or patterns, the direct printing ofsilver-containing inks provides attractive prospects for making suchelectrically-conductive patterns.

Inkjet printing and flexographic printing have also been proposed forproviding patterns of silver or silver-containing compounds, requiringthe careful fabrication of a silver-containing paste or “ink” withdesirable surface tension, viscosity, stability, and other physicalproperties required for such application processes. High silver contenthas generally been required for high electrical conductivity, andcalcination or sintering may be additionally required for increasingelectrical conductivity of printed silver inks.

Some approaches to providing silver metal is to employ a chemical inkformulation where the silver source is a molecular precursor or cation(such as a silver salt) that is then chemically reacted (or reduced) toproduce silver metal. Electrically-conductive inks that are in the formof a chemical solution rather than as a suspension or dispersion ofmetal particles, have gained interest in recent years. One conductiveink of this type is known as a Metalorganic Decomposition (MOD) varietyink, for example, as described by Jahn et al. [Chem. Mater. 22,3067-3071 (2010)] who investigated silver printing using an aqueoustransition metal complex [AgO₂C(CH₂OCH₂)₃H]-containing MOD ink. Theyreported the formation of metallic silver features having electricalconductivities as high as 2.7×10⁷ S m⁻¹, which corresponds to anelectrical conductivity that is 43% of that of bulk silver, although asintering temperature of 250° C. was required.

U.S. Patent Application Publication 2015-0004325 (Walker et al.)describes a chemically-reactive silver ink composition comprised of acomplex of a silver carboxylate salt and an alkylamine, in which thecomplex is used to form an electrically-conductive silver structure at atemperature of 120° C. or less. Unfortunately, even these temperaturesrender the ink incompatible with many polymeric and paper substratesused in flexible electronic and biomedical devices. Furthermore, sincealkylamines are known to reduce silver at room temperature, long termstability of such compositions is tentative. Furthermore, thepublication teaches long heating times were needed to obtain lowresistivity in the resulting articles.

U.S. Pat. No. 8,419,822 (Li) describes a process for producingcarboxylic acid-stabilized silver nanoparticles by heating a mixture ofa silver salt, a carboxylic acid, and a tertiary amine. However, it hasbeen observed that such silver-containing complexes are not thermally orlight stable as the reducible silver ions are readily reduced underambient light conditions, and the resulting electrical conductivity ofsilver particles is minimal.

Other industrial approaches to preparing electrically-conductive filmsor elements have been directed to formulating and applying photocurablecompositions containing dispersions of metal particles such as silvermetal particles to substrates, followed by curing the photocurablecomponents in the photocurable compositions. The applied silverparticles in the cured compositions can act as catalytic (seed)particles for electrolessly plated electrically-conductive metals.Useful electrically-conductive grids prepared in this manner aredescribed for example, in U.S. Pat. No. 9,188,861 (Shukla et al.) andU.S. Pat. No. 9,207,533 (Shukla et al.) and in US Patent ApplicationPublications 2014/0071356 (Petcavich) and 2015/0125596 (Ramakrishnan etal.). Using these methods, photocurable compositions containingcatalytic silver particles can be printed and cured on a suitabletransparent substrate, for example a continuous roll of a transparentpolyester film, and then electroless metal plating can be carried out onthe catalytic silver particles. However, these methods require that highquantities of purchased silver particles be uniformly dispersed withinthe photocurable compositions so that coatings or printed patterns havesufficiently high concentration of catalytic sites. Without effectivedispersing, silver particles readily agglomerate, leading to lessineffective electroless plating and electrical conductivity.

Moreover, forming stable patterns of silver particles in this mannerrequires the presence of photosensitive components such as polymerizablemonomers or crosslinkable polymers that must be exposed to suitableradiation. Scaling such curing procedures to high volume use can bedifficult and hard to reproduce on a consistent scale, especially forthe production of fine line electrically-conductive meshes or gridswhere the uniformity and size of fine lines are subjected to highlyrigorous standards.

Efforts are being directed in the industry to avoid the need forphotocuring. For, example, U.S. Patent Application Publication2012/0225126 (Geckeler et al.) describes a solid state method forpreparing silver nanoparticles using a mixture of a silver salt and awater-soluble polymer such as a starch or cellulose derivative that actsas a silver ion reducing agent. The mixture is milled by a high-speedvibration milling process to form silver nanoparticles within thewater-soluble starch or cellulosic polymer so that a solvent is notneeded for synthesis or transportation of the silver nanoparticles.

Cellulose is a polydisperse linear homopolymer consisting ofregioselective and enantioselective β-1,4-glycosidic linked D-glucoseunits. The homopolymer contains three reactive hydroxyl groups at theC-2, C-3 and C-6 atoms that are in general, accessible to the typicalchemical conversions of primary and secondary —OH groups.

The use of cellulose together with its derivatives has wide spreadapplications, for example in fibers, films, plastics, coatings,suspension agents, composites. With the advent of synthetic polymers,their uses have somewhat diminished, but cellulose derivatives are stillthe raw materials of choice for some uses. In addition, various studiesare on-going to look for and expand their use in existing and newtechnologies. Cellulosic polymers can be considered renewable resourcesin some instances. An inherent problem that faces users of cellulosicpolymers is their general insolubility in most common solvents.Modifying the structure of cellulosic polymers can improve theirsolubility, leading to the synthesis of various cellulose derivatives(cellulosics) that come in all forms and structures depending on thefunctional group(s) used in place of the hydroxyl groups on thecellulose chain.

For example, cellulose derivatization can involve partial or fullesterification or etherification of the hydroxyl groups on the cellulosechain by reaction with various reagents to afford cellulose derivativeslike cellulose esters and cellulose ethers. Among all cellulosederivatives, cellulose acetate is recognized as the most importantorganic ester of cellulose owing to its extensive industrial andcommercial importance. It has many uses such as in the production ofplastic films, lacquers, photographic films, thermoplastic mouldings,transparent sheeting, camera accessories, magnetic tapes, combs,telephone, and electrical parts. Other common cellulose esters includecellulose acetate butyrate and cellulose acetate propionate, both ofwhich are used in inks and coatings. Among some common cellulose ethersare methyl cellulose, hydroxyethyl cellulose, and carboxymethylcellulose (CMC).

Properties of cellulose derivatives (esters and ethers) are determinedprimarily by the functional group. However, they can be modifiedsignificantly by adjusting the degree of functionalization and thedegree of polymerization of the polymer backbone. For example, the chiefdifference between cellulose acetate butyrate and cellulose acetatepropionate and precursor cellulose acetate is their solubility in awider range of solvents.

Thus, cellulose derivatives exhibit different solution propertiesdepending on the solvent system and the functional group(s) used tosubstitute the hydroxyl group(s) on cellulose chain. Cellulose esterssuch as cellulose nitrate and cellulose acetate dissolve in a wide rangeof solvents such as both aqueous and common organic solvents such aschloroform (CHCl₃), acetone, and N,N-dimethylformamide (DMF).

Solution to gel transitions have been observed in various cellulosederivatives, forming mostly physical gel systems. It is widely acceptedthat gelation is initiated by large macromolecular association leadingto the formation of a three-dimensional network extending through theentire volume of the system (see Iliyna and Daragan in Macromolecules1994, 27, 3759-3763). The transitions from solutions to gels have beenstudied using various techniques including rheological methods. Rheologyhas been determined to be the most direct method to determine sol-geltransitions in polymeric systems.

The solution properties of cellulose acetates have been well studied andhave been shown to be influenced by the average degree of substitutionand the distribution of substituents along the chain. Previous work onthe gelation mechanism of cellulose acetate has shown interestingbehavior with respect to the sol-gel transition. Cellulose acetate gelsexhibit thermal reversible properties that depend on factors such asconcentration, acetyl content, and the type of solvent. It is usuallydifficult to predict if cellulose will gel in a given organic solvent,and in most cellulose acetate/solvent systems, gelation occurs after thesolution is heated to a specific temperature and subsequently cooled.For example, Kwon et al., Bull. Korean Chem. Soc. 26(5), 837-840describe a study of silver nanoparticles in cellulose acetate solutions.

Despite all of the various approaches and efforts to provideelectrically-conductive silver in various consumer and industrialarticles described above, there remains a need for simpler and lessexpensive compositions and methods for generation of silvernanoparticles in a fashion suitable particularly for pattern formationin high speed manufacturing and electroless plating processes withoutthe need for photocuring and complicated processes for makingdispersions.

SUMMARY OF THE INVENTION

The present invention provides an article comprising a substrate, andhaving disposed on a supporting surface thereof a pattern of a drysilver nanoparticle-containing composition comprising:

at least 20 weight % of one or more (a) polymers, based on the totalweight of the pattern, which one or more (a) polymers are selected fromone or more of cellulose acetate, cellulose acetate phthalate, celluloseacetate butyrate, cellulose acetate propionate, cellulose acetatetrimellitate, hydroxypropylmethyl cellulose phthalate, methyl cellulose,ethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose,hydroxypropylmethyl cellulose, and carboxymethyl cellulose;

(d) silver nanoparticles having a mean particle size of at least 25 nmand up to and including 750 nm, that are present in the pattern in anamount of at least 0.1 weight % and up to and including 400 weight %,based on the total weight of the one or more (a) polymers;

(e) carbon black in an amount of at least 5 weight % and up to andincluding 50 weight %, based on the total weight of the one or more (a)polymers; and

less than 5 mol % of (b) reducible silver ions, based on the total molaramount of silver in the silver nanoparticle-containing composition.

This “precursor” article can be transformed in a product article byelectrolessly plating the pattern with a suitable metal as describedbelow.

The present invention provides a simple and inexpensive way to generatesilver nanoparticles within a non-aqueous silver precursor compositioncomprising reducible silver ions and a cellulosic polymer, therebycreating a non-aqueous silver nanoparticle-containing composition. Themethod according to this invention can be readily used for manufacturinghigh weight fraction fully dispersed silver nanoparticles. Thenon-aqueous silver nanoparticle-containing compositions according to thepresent invention have long term stability as the silver nanoparticlesdo not readily agglomerate. These silver nanoparticle-containingcompositions can be easily deposited or formed into patterns, and suchpatterns can be readily electrolessly plated with copper or anotherelectrically-conductive metal. Thus, the use of preformed silvernanoparticles that must be kept dispersed within a solvent medium usingbinders or dispersants or complex formulations is avoided. In addition,the silver nano-particle-containing compositions do not require frequentmixing for uniformity and articles can be prepared according to thepresent invention without the need for photocuring.

The present invention provides these advantages by means of thermaltreatment of the non-aqueous reducible silver ion precursor compositionscomprising certain cellulosic polymers as silver ion reducing agents,and one or more organic solvents. The particular cellulosic polymers andorganic solvents used in the non-aqueous silver precursor compositionsthus facilitate silver ion reduction and provide physical stability ofthe resulting silver nanoparticles. The inventive compositions andmethods can thus be used to provide precursor articles having appliedsilver nanoparticles, for example, in one or more patterns; and productarticles that have electrolessly plated metals such as copper, incorresponding patterns.

Other advantages of the present invention would be readily apparent toone skilled in the art in view of the teaching provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical representation of Absorbance vs. Wavelength (nm)for the silver nanoparticle evaluation described in Invention Example 1below.

FIG. 2 is a graphical representation of a bimodal silver nanoparticlesize distribution as described for Invention Example 1 below.

FIG. 3, is a graphical representation of G′ and G″ values used todetermine Tan (δ) values for the rheological evaluation of a non-aqueoussilver nanoparticle-containing composition described below in InventionExample 1.

FIG. 4 is a magnified microscopic image of an electrolessly copperplated pattern as described below in Invention Example 2.

FIG. 5 is a graphical representation of Absorbance vs. Wavelength (nm)for the silver nanoparticle evaluation described below in InventionExample 3.

FIG. 6 is a graphical representation of Absorbance vs. Wavelength (nm)for the silver nanoparticle evaluation described below in InventionExample 5.

FIG. 7 is a graphical representation of Absorbance vs. Wavelength (nm)for the silver nanoparticle evaluation described below in InventionExample 6.

FIG. 8 is a graphical representation of a trimodal silver nanoparticlesize distribution as described below for Invention Example 6.

FIG. 9 is a magnified microscopic image of an electrolessly copperplated pattern as described below in Invention Example 7.

FIG. 10 is a graphical representation of Absorbance vs. Wavelength (nm)for the silver nanoparticle evaluation for Invention Example 8 below.

DETAILED DESCRIPTION OF THE INVENTION

The following discussion is directed to various embodiments of thepresent invention and while some embodiments can be desirable forspecific uses, the disclosed embodiments should not be interpreted orotherwise considered be limit the scope of the present invention, asclaimed below. In addition, one skilled in the art will understand thatthe following disclosure has broader application than is explicitlydescribed and the discussion of any embodiment.

Definitions

As used herein to define various components of the non-aqueous silverprecursor composition, unless otherwise indicated, the singular forms“a,” “an,” and “the” are intended to include one or more of thecomponents (that is, including plurality referents).

Each term that is not explicitly defined in the present application isto be understood to have a meaning that is commonly accepted by thoseskilled in the art. If the construction of a term would render itmeaningless or essentially meaningless in its context, the termdefinition should be taken from a standard dictionary.

The use of numerical values in the various ranges specified herein,unless otherwise expressly indicated otherwise, are considered to beapproximations as though the minimum and maximum values within thestated ranges were both preceded by the word “about.” In this manner,slight variations above and below the stated ranges can be used toachieve substantially the same results as the values within the ranges.In addition, the disclosure of these ranges is intended as a continuousrange including every value between the minimum and maximum values.

Unless otherwise indicated, the term “weight %” refers to the amount ofa component or material based on the total amount of a non-aqueoussilver precursor composition or non-aqueous silvernanoparticle-containing composition. In other embodiments, “weight %”can refer to the % solids (or dry weight) of a dry layer, coating, thinfilm, silver wire, or silver-containing pattern.

Unless otherwise indicated, the term “non-aqueous” as applied to thenon-aqueous silver precursor compositions and non-aqueous silvernanoparticle-containing compositions means that solvent media used toform such compositions are predominantly organic in nature and water isnot purposely added but may be present in an amount of less than 5weight % by virtue of being part of a chemical component, orparticularly less than 1 weight %, or even less than 0.1 weight %, ofthe total weight of all solvents in the composition.

Unless otherwise indicated, the term “non-aqueous silver precursorcomposition” means that the silver present therein is predominantly(greater than 50 weight % of total silver) in the form of reduciblesilver ions.

Average dry thickness of silver nanoparticle-containing lines, gridlines, or other pattern features described herein can be the average ofat least 2 separate measurements taken, for example, using electronmicroscopy, optical microscopy, or profilometry all of which shouldprovide substantially the same results for the same test sample.

The use of “dry” in reference to thickness and width of lines, patterns,or layers, refers to embodiments in which at least 80 weight % oforiginally present organic solvent(s) has been removed.

As used herein for defining silver nanoparticles, “mean particle size”is measured using dynamic light scattering (DLS), that is sometimesreferred to as Quasi-Elastic Light Scattering (QELS), and is awell-established technique for measuring the size and size distributionof molecules and particles typically in the submicron region, and evenlower than 1 nm. Commercial DLS instruments are available from, forexample Malvern and Horiba who also supply instructions for use of suchequipment, and such equipment and accompany instructions can be used tocharacterize and carry out the present invention.

Boiling point of organic solvents described herein can be determinedfrom known publications or measured using standard methods.

Unless otherwise indicated herein, viscosity can be determined at 25° C.using any standard commercially available viscometer.

Unless otherwise indicated, the term “group” particularly when used todefine a substituent or a moiety, can itself be substituted orunsubstituted (for example an “alkyl group” refers to a substituted orunsubstituted alkyl group) by replacement of one or more hydrogen atomswith suitable substituents (noted below) such as a fluorine atom.Generally, unless otherwise specifically stated, substituents on any“groups” referenced herein or where something is stated to be possiblysubstituted, include the possibility of any groups, whether substitutedor unsubstituted, which do not destroy properties necessary for theutility of the component or non-aqueous silver precursor composition. Itwill also be understood for this disclosure and claims that reference toa compound or complex of a particular general structure includes thosecompounds of other more specific formula that fall within the generalstructural definition. Examples of substituents on any of the mentionedgroups can include known substituents such as: halogen (for example,chloro and fluoro); alkoxy, particularly those with 1 to 5 carbon atoms(for example, methoxy and ethoxy); substituted or unsubstituted alkylgroups, particularly lower alkyl groups (for example, methyl andtrifluoromethyl), particularly either of those having 1 to 6 carbonatoms (for example, methyl, ethyl, and t-butyl); and other substituentsthat would be readily apparent in the art.

Unless otherwise indicated, all voltages described herein are measuredversus SCE (saturated calomel electrode).

Uses

The deposition or patterning of functional electrodes, pixel pads, andconductive traces, lines and tracks, that meets electrical conductivity,processing, and cost requirements for practical applications has been agreat challenge. Silver metal is of particular interest in thepreparation of electrically-conductive elements for use in electronicdevices because silver can be readily electrolessly plated for exampleusing highly electrically-conductive copper.

The inventive non-aqueous reducible silver ion compositions describedherein can be used for forming metallic silver patterns and electrodesfor example in membrane touch switches (MTS), battery testers,biomedical, electroluminescent lamps, radio frequency identification(RFID) antenna, flat panel displays such as plasma display panel (PDP)and organic light emitting diode (OLED) displays, printed transistorsand thin film photovoltaics, and thereby reduce the numbers of steps forpattern formation in such devices.

The non-aqueous silver precursor compositions described herein have anumber of actual and potential uses in various technologies andindustries. Most specifically, they can be used to provide silver metalfor various purposes, including but not limited to, the formation ofelectrically-conductive grids or patterns of fine wires or othergeometric forms, the formation of silver seed particles for electrolessplating with other electrically-conductive metals, and the formation ofsilver in various materials for antimicrobial activity.

More specifically, the non-aqueous silver precursor compositionsaccording to the present invention are particularly useful to providesilver metal as part of electrically-conductive metal patterns that arethen electrolessly plated to provide electrically-conductive patterns.These electrically-conductive metal patterns can be incorporated intovarious devices including but not limited to, touch screens or othertransparent display devices, and in modern electronics such as solarcell electrodes, electrodes in organic thin film transistors (OTFTs),flexible displays, radio frequency identification tags, light antennas,and other devices that would be readily apparent to one skilled in theart from the teaching herein. For example, silver nanoparticles formedaccording to the present invention can be used as catalytic sites forelectrochemical (electroless) plating using copper or other metals toimprove electrical conductivity of the resulting patterns.

Non-Aqueous Silver Precursor Compositions

In all embodiments, the non-aqueous silver precursor compositionsaccording to the present invention contain three essential componentsfor purposes of providing silver metal in the form of silvernanoparticles according to the present invention: one or more (a)polymers (cellulosic polymers) as described below; (b) reducible silverions in the form of one or more silver salts or silver complexes asdescribed below; and (c) an organic solvent medium consisting of (i) oneor more hydroxylic organic solvents, and optionally one or more (ii)nitrile-containing aprotic or carbonate-containing aprotic solvents, ormixtures of both, all of which are different from the (i) hydroxylicorganic solvents, as described below. No other components are purposelyadded to the non-aqueous silver precursor compositions according to thepresent invention, and as noted above, water is not purposely included.As described below, for some non-aqueous silver nanoparticle-containingcompositions, (e) carbon black can be present as a fourth essentialcomponent for such compositions.

Upon thermal treatment as described below, the non-aqueous silverprecursor composition according to this invention can be converted intoa corresponding non-aqueous silver nanoparticle-containing compositioncomprising (d) silver nanoparticles in an amount of at least 0.1 weight% based on (or relative to) the total weight of the one or more (a)polymers. It is desirable that at least 90 mol %, at least 95 mol %, oreven at least 98 mol % (which means “substantially all”) of the (b)reducible silver ions are converted to (d) silver nanoparticles duringthis process.

The one or more (a) polymers, (b) reducible silver ions, (c) organicsolvent medium can be combined in general by mixing them under suitableambient conditions so that thermal reduction does not occur prematurelyto any appreciable extent. Thus, components (a) and (b) can be added tothe (c) organic solvent medium in any suitable order.

In general, the % solids of the non-aqueous silver precursor compositionis at least 1% and up to and including 50%, or more typically of atleast 5% and up to and including 20%. The amount of solids and (c)organic solvent medium, and viscosity, can thus be adjusted for aparticular use.

The non-aqueous silver precursor composition is generally provided inliquid form having a viscosity of at least 1 centipoise (0.001 Pascalsec) and up to and including 5,000 centipoise (5 Pascal sec), or morelikely a viscosity of at least 3 centipoise (0.003 Pascal sec) and up toand including 10 centipoise (0.01 Pascal sec), all measured at 25° C.

The non-aqueous silver nanoparticle-containing composition can have thesame or different viscosity as the corresponding non-aqueous silverprecursor composition. In most embodiments, the two compositions haveessentially the same viscosity, that no more than 10% difference.

(a) Polymers:

The polymers useful in the practice of the present invention are organicin nature, and can be used singly or in mixtures of two or moredifferent materials. When used in mixtures, the two or more differentmaterials can be present in the same or different amounts within thetotal polymer amount. Both cellulose esters and cellulose ethers can beused in the present invention.

Representative useful polymers for the practice of the present inventionare selected from one or more of cellulose acetate, cellulose acetatephthalate, cellulose acetate butyrate, cellulose acetate propionate,cellulose acetate trimellitate, hydroxypropylmethyl cellulose phthalate,methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxyethylcellulose, hydroxypropylmethyl cellulose, and carboxymethyl cellulose.

Particularly useful polymers according to the present invention includecarboxymethyl cellulose, cellulose acetate butyrate, cellulose acetatepropionate, cellulose acetate, and hydroxypropyl cellulose, individuallyor in mixtures.

The one or more polymers are present in a total amount of at least 1weight % and up to and including 99.9 weight %, or more likely of atleast 5 weight % and up to and including 30 weight %, or up to andincluding 50 weight %, based on the total weight of the non-aqueoussilver precursor composition (including all solid materials and theorganic solvent medium), or based on the total weight of the non-aqueoussilver nanoparticle-containing composition.

Each of the useful polymers can be readily obtained from variouscommercial sources in the world, or they can be prepared using knownstarting materials, reaction conditions, and known synthetic procedures.

(b) Reducible Silver Ions:

Reducible silver ions can be provided in the non-aqueous silverprecursor composition from many various sources as long as the silversalt or silver complex in which they are provided is soluble within the(c) organic solvent medium. For such silver salts and silver complexes,each has a solubility in a given (c) organic solvent medium of at least1 g/liter at 20° C.

In general, silver salts or silver complexes comprised of any suitableorganic or inorganic anion or complexed moiety (or combination of anionsand complexed moieties) can be used in the practice of the presentinvention to provide the (b) reducible silver ions. Such silvercomplexes can be mononuclear, dinuclear, trinuclear, or higher and eachcompound generally has a net neutral charge. The following classes ofuseful reducible silver ion-containing salts and reducible silverion-containing complexes are described as representative materials, butthe present invention is not to be interpreted to be limited to them.Such reducible silver ion-containing materials can be readily purchasedfrom various commercial sources or prepared using known procedures,starting materials, and reaction conditions, unless otherwise indicated.

(i) A first class of reducible silver ion-containing compounds aresilver salts having organic or inorganic anions. Some representativesilver salts include but not limited to, silver nitrate, silver acetate,silver benzoate, silver nitrite, silver thiocyanate, silver myristate,silver citrate, silver phenylacetate, silver malonate, silver succinate,silver adipate, silver phosphate, silver perchlorate, silveracetylacetonate, silver lactate, silver salicylate, silver oxalate,silver 2-phenylpyridine, silver trifluoroacetate; silver fluoride andsilver fluoride complexes such as silver (I) fluorosulfate, silver (I)trifluoroacetate, silver (I) trifluoromethane sulfate, silver (I)pentafluoropropionate, and silver (I) heptafluorobutyrate; β-carbonylketone silver (I) complexes; silver proteins; and derivatives of any ofthese materials.

Useful silver complexes can be readily prepared using known proceduresand some can be purchased from commercial sources.

(ii) Complexes of hindered aromatic N-heterocycle with (b) reduciblesilver ions can be used in the practice of this invention. The term“hindered” as used to define hindered aromatic N-heterocycle means thatthe moiety has a “bulky” group that is located in the α position to thenitrogen atom in the aromatic ring. Such bulky groups can be definedusing the known “A-value” parameter that is a numerical value used forthe determination of the most stable orientation of atoms in a molecule(using conformational analysis) as well as a general representation ofsteric bulk. A-values are derived from energy measurements of amono-substituted cyclohexane ring. Substituents on a cyclohexane ringprefer to reside in the equatorial position to the axial. In the presentinvention, the useful “bulky” groups in the hindered aromaticN-heterocycle have an A-value of at least 0.05. Useful reducible silverion-containing complexes of this type are described in U.S. Pat. No.9,377,688 (Shukla), the disclosure of which is incorporated herein byreference for a further description of properties, representativecompounds, and methods for preparing them.

(ii) Other useful complexes comprise (b) reducible silver ions aresilver carboxylate-trialkyl, carboxylate-triaryl, andcarboxylate-alkylaryl phosphite complexes and mixtures of thesecompounds. The terms “carboxylate-trialkyl phosphite” and“carboxylate-triaryl phosphite” are to be interpreted herein asindicating that the complex of which it is a part can have three of thesame or different alkyl groups, or three of the same or different arylgroups, respectively. The term “carboxylate-alkylaryl phosphite” refersto a compound having a mixture of a total of three alkyl and arylgroups, in any combination. Useful reducible silver ion-containingcomplexes of this type are described in U.S. Pat. No. 9,375,704(Shukla), the disclosure of which is incorporated herein by referencefor a further description of properties, representative compounds, andmethods for preparing them.

(iii) Silver-oxime complexes can be used to provide (b) reducible silverions, and these materials are generally non-polymeric in nature (meaningthat the silver complex molecular weight is less than 3,000). Usefulnon-polymeric silver-oxime complexes of this type are described in U.S.Pat. No. 9,387,460 (Shukla), the disclosure of which is incorporatedherein by reference for a further description of properties,representative compounds, and methods for preparing them.

(iv) Other useful silver complexes comprising (b) reducible silver ionscan be represented by the following Structure (V):(Ag⁺)_(a)(L)_(b)(P)_(c)   (V)wherein L represents an α-oxy carboxylate; P represents a 5- or6-membered N-heteroaromatic compound; a is 1 or 2; b is 1 or 2; and c is1, 2, 3, or 4, provided that when a is 1, b is 1, and when a is 2, b is2.

Each of the complexes of Structure (V) comprises one or two reduciblesilver ions. Each reducible silver ion is complexed with one or twoα-oxy carboxylate compounds that can be via two oxygen atoms providedfrom the same molecule of an α-oxy carboxylate compound, or oxygen atomsprovided from two molecules of the same or different α-oxy carboxylatecompounds.

The α-oxy carboxylate groups (moieties or components) can be defined inwhich the α-carbon atom attached directly to the carboxyl group[—C(═O)O-] has a hydroxy group, oxy, or an oxyalkyl substituent group.Thus, the α-oxy carboxylates can be either α-hydroxy carboxylates,α-alkoxy carboxylates, or α-oxy carboxylates. With the α-hydroxycarboxylates and α-alkoxy carboxylates, the remainder of the valences ofthat α-carbon atom can be filled with hydrogen or a branched or linearalkyl group (substituted or unsubstituted) as described below in moredetail. In addition, the α-oxy carboxylate (L) generally has a molecularweight of 250 or less, or 150 or less.

In Structure (V) shown above, b is 1 or 2, and in the embodiments whereb is 2, the two α-oxy carboxylate compounds within a single complexmolecule can be the same or different compounds. In some embodiments ofthe present invention, L of Structure (V) described above can berepresented by the following Structure (VI):

wherein R₁, R₂, and R₃ are independently hydrogen or branched or linearalkyl groups. In most embodiments, at least one of R₁ through R₃ is abranched or linear alkyl group having from 1 to 8 carbon atoms, and anyof the hydrogen atoms in such branched or linear alkyl groups can bereplaced with a heteroatom such as a fluorine atom substituent.

Some particularly useful conjugate acids from which α-oxy carboxylates(L) of Structure (VI) can be selected from the group consisting oflactic acid, 2-hydroxybutyric acid, 2-hydroxy-3-methylbutyric acid,2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-isobutyric acid,2-hydroxy-2-methylbutyric acid, 2-ethyl-2-hydroxybutyric acid,2-hydroxy-2,3-dimethylbutyric acid, 2-ethyl-2-methoxybutyric acid,2-methoxy-2-methylpropanoic acid, 1-hydroxycyclopentane-1-carboxylicacid, 2,3-dihydroxy-2,3-dimethylsuccinic acid, and2,4-dihydroxy-2,4-dimethylpentanedioic acid. As noted above, mixtures ofthese materials can be used in a specific complex if desired.

In other embodiments, L is represented in Structure (V) by the followingStructure (VII):

wherein R₄ is a branched or linear alkyl group having 1 to 8 carbonatoms, including branched iso- and tertiary alkyl groups having 3 to 8carbon atoms. In addition, any of the hydrogen atoms in any of thebranched or linear alkyl groups optionally can be replaced with afluorine atom; for example, the terminal carbon atom of a R₄ branched orlinear alkyl group can have 1 to 3 fluorine atoms.

Some useful conjugate acids from which the α-oxy carboxylate (L)represented by Structure (VII) can be selected from the group consistingof pyruvic acid, 3-methylpyruvic acid, 3,3-dimethylpyruvic acid,3,3-dimethyl-2-oxobutanoic acid, 3,3-dimethyl-2-oxopentanoic acid, and2,3-dioxosuccinic acid.

The “P” compound of Structure (V) is a 5- or 6-membered N-heteroaromaticcompound such as a 6-membered N-heteroaromatic compound. Such 5- or6-membered N-heteroaromatic compounds can have a pK_(a) of at least 10and up to and including 22. An experimental method for measuring pK_(a)and the pK_(a) values of some N-heteroaromatic bases are known (forexample, see Kalijurand et al. J. Org. Chem. 2005, 70, 1019).

In general, each 5- or 6-membered N-heteroaromatic compound isnon-polymeric in nature and has a molecular weight of 200 or less. By“5- or 6-membered,” it is meant that the N-heteroaromatic compound haseither 5 or 6 atoms in the heterocyclic aromatic ring, at least one ofwhich atoms is a nitrogen atom. In general, such heterocyclic aromaticrings generally have at least one carbon atom and at least one nitrogenatom in the ring.

In Structure (V) shown above, c is 1, 2, 3, or 4, and in the embodimentswhere c is 2, 3, or 4, the multiple 5- or 6-membered N-heteroaromaticcompound molecules within the single complex molecule can be the same ordifferent. For example, the 5- or 6-membered N-heteroaromatic compoundcan be selected from the group consisting of pyridine, 2-methylpyridine,4-methylpyridine, 2,6-dimethylpyridine, 2,3-dimethylpyridine,3,4-dimethylpyridine, 4-pyridylacetone, 3-chloropyridine,3-fluoropyridine, oxazole, 4-methyloxazole, isoxazole,3-methylisoxazole, pyrimidine, pyrazine, pyridazine, and thiazole.

Representative 5- or 6-membered N-heteroaromatic compounds can bereadily obtained from various commercial chemical suppliers located invarious countries.

Further details of properties, representative compounds, and methods ofmaking them are provided in copending and commonly assigned U.S. Ser.No. 15/231,804 (filed Aug. 9, 2016 by Shukla), the disclosure of whichis incorporated herein by reference. Of these types of reducible silverion-containing complexes, a silver α-oxycarboxylate pyridine complexsuch as silver lactate pyridine complex, is particularly useful.

(v) Still other useful silver complexes are designed with one or two (b)reducible silver ions as described above for the (iv) silver complexes,complexed with both one or two α-oxy carboxylate molecules as describedabove for the (iv) silver complexes, and one, two, three, or fourprimary alkylamine molecules. In general, such useful silver complexescan be represented by the following Structure (VIII):(Ag⁺)_(a)(L)_(b)(P)_(c)   (VIII)wherein L represents the α-oxy carboxylate; P represents the primaryalkylamine; a is 1 or 2; b is 1 or 2; and c is 1, 2, 3, or 4, providedthat when a is 1, b is 1, and when a is 2, b is 2.

In such complexes, P is a primary alkylamine having a boiling point ofless than or equal to 175° C., or having a boiling point of less than orequal to 125° C., or even at least 75° C. and up to and including 125°C., at atmospheric pressure. The useful primary alkyl amines thatgenerally have a molecular weight of less than 500 and are thusconsidered “non-polymeric” as defined by molecular weight and boilingpoint.

The term “primary alkylamine” refers herein to compounds that arenon-aromatic and are not cyclic in structure. They generally have a oneor more nitrogen atoms as long as all other features (molecular weight,pKa, boiling point, and oxidation potential) described herein are met.In such compounds, each of the nitrogen atoms has two valences filled byhydrogen atoms and the remaining valence of each nitrogen atom is filledwith a substituted or unsubstituted alkyl group (not including alkylarylgroups such as benzyl groups), or with a substituted or unsubstitutedalkylene group for compounds defined herein as “primary alkyl diamines”that can be illustrated by the following Structure (IX):H₂N—R₅—NH₂   (IX)wherein R₅ represents a substituted or unsubstituted, branched orlinear, divalent alkylene group having 1 to 5 carbon atoms; and optionalsubstituents include but are not limited to, fluoride atoms for any ofthe hydrogen atoms in the alkylene group.

In most useful embodiments, the primary alkyl amines comprise a singlenitrogen atom and a single substituted or unsubstituted, branched orlinear alkyl group having at least 3 carbon atoms, and generally from 3to 6 carbon atoms, wherein any of the hydrogen atoms of the alkyl groupcan be replaced with a fluorine atom.

Representative useful primary alkylamines can be selected from the groupconsisting of a propylamine, n-butylamine, t-butylamine, isopropylamine,2,2,2-trifluoroethylamine, 2,2,3,3,3-pentafluoropropylamine,3,3,3-trifluoropropylamine, 1,2-dimethylpropylamine, t-amyl amine, andisopentylamine. Other useful primary alkylamines would be readilyapparent to one skilled in the art. In some embodiments, the primaryamine has an asymmetric carbon center on an alkyl chain. Some examplesof such amines include but not limited to, a 2-amino-3-methylbutane,3,3-dimethyl-2-butylamine, 2-aminohexane, sec-butylamine, and othersthat would be readily apparent to one skilled in the art from theforegoing description. Such primary alkylamines can be substituted withother groups that would be readily apparent to one skilled in the art.

Useful primary alkyl amines can be readily obtained from variousworldwide commercial sources of chemicals.

Further details of properties, representative compounds, and methods ofmaking them are provided in copending and commonly assigned U.S. Ser.No. 15/231,837 (filed Aug. 9, 2016 by Shukla), the disclosure of whichis incorporated herein by reference.

(vi) Yet other useful reducible silver ion-containing complexes aredesigned with one or two (b) reducible silver ions as described abovefor the (iv) silver complexes, complexed with both one or two α-oxycarboxylate molecules as described above for the (iv) silver complexes,and one, two, three, or four oxime compound molecules. In general, eachuseful silver complex can be represented by the following Structure (X):(Ag⁺)_(a)(L)_(b)(P)_(c)   (X)wherein L represents the α-oxy carboxylate; P represents an oximecompound; a is 1 or 2; b is 1 or 2; and c is 1, 2, 3, or 4, providedthat when a is 1, b is 1, and when a is 2, b is 2.

In the noted Structure (X), the “P” compound is an oxime compound (or amixture of two or more different oxime compounds). Traditionally, an“oxime” has a general formula of >C═N—OH. In the present invention, theterm “oxime compound” is meant to include such compounds as well ascompounds in which the hydrogen is replaced with a suitable monovalentradical. In general, the oxime compounds useful herein are not polymericin nature and each has a molecular weight of 200 or less, or of 150 orless.

In Structure (X) shown above, c is 1, 2, 3, or 4, and in the embodimentswhere c is 2, 3, or 4, the P molecules within the single complexmolecule can be the same or different oxime compounds.

For many embodiments, P can be an oxime compound that can be representedby the following Structure (XI):

wherein R₅ and R₆ are independently hydrogen or a substituted orunsubstituted alkyl group having 1 to 6 carbon atoms (linear orbranched), provided that at least one of R₅ and R₆ is one of such alkylgroups. Alternatively, R₅ and R₆ can together represent the carbon atomssufficient to provide a substituted or unsubstituted 5- or 6-membered,saturated carbocyclic ring, such as a substituted or unsubstitutedpentane ring or substituted or unsubstituted cyclohexane ring.

R₇ is hydrogen, a substituted or unsubstituted alkyl group having 1 to 6carbon atoms (linear or branched), a substituted or unsubstituted acylgroup having 1 to 6 carbon atoms (linear or branched), a —C(═O)R₈ group,or a carbonyloxyalkyl group [—C(═O)OR₈], wherein R₈ is hydrogen or asubstituted or unsubstituted alkyl having 1 to 6 carbon atoms (linear orbranched).

Representative oxime compounds useful in the practice of the presentinvention include but are not limited to, acetoxime (acetone oxime),acetaldoxime, Aldicarb, dimethylglyoxime, methylethyl ketone oxime,propionaldehyde oxime, cyclohexanone oxime, cyclopentanone oxime,heptanal oxime, acetone-O-methyl oxime, acetaldehyde-O-methyl oxime,propionaldehyde-O-methyl oxime, butanaldehyde-O-methyl oxime,2-butanone-O-methyl oxime, cyclopentanone-O-methyl oxime, and2-butanone-O-ethyl oxime.

Some representative oxime compounds can be readily obtained from variouscommercial chemical suppliers such as Sigma Aldrich. Further details ofproperties, representative examples, and methods of making them areprovided in copending and commonly assigned U.S. Ser. No. 15/362,868(filed Nov. 29, 2016 by Shukla et al.), the disclosure of which isincorporated herein by reference.

In the non-aqueous silver precursor compositions according to thepresent invention, the amounts of the (b) reducible silver ions can bevaried depending upon the particular manner in which the composition isto be used. For example, when the non-aqueous silver precursorcomposition is designed for the formation of fine lines containingsilver nanoparticles, such as in fine line grids or meshes, the amountof (b) reducible silver ions is generally at least 0.1 weight % and upto and including 400 weight %, or typically at least 0.1 weight % and upto and including 200 weight %, or even at least 15 weight % and up toand including 50 weight %, all based on (or relative to) the totalweight of the one or more (a) polymers (defined above). Such fine linescan generally have an average dry width of less than 20 μm, or moretypically of less than or equal to 15 μm, and for example of at least0.1 μm and up to and including 15 μm; and a dry height of less than 2 μmor typically less than 1 μm.

However, in those embodiments, where a uniform layer containing silvernanoparticles is desired, or where “large areas” (larger than the finelines described above) are found, the amount of (b) reducible silverions in the non-aqueous silver precursor compositions can be as low asat least 0.1 weight % and up to and including 5 weight %, or at least0.25 weight % and up to and including 4 weight %, all based on (orrelative to) the total weight of the one or more (a) polymers (definedabove).

(c) Organic Solvent Medium:

In all embodiments of the non-aqueous silver precursor composition, the(a) and (b) components are dispersed or dissolved in an (c) organicsolvent medium that consists of (i) one or more hydroxylic organicsolvents, each of which has an α-hydrogen atom and properties definedbelow. This (c) organic solvent medium can also contain in someembodiments, (ii) one or more nitrile-containing aprotic solvents, oneor more carbonate-containing aprotic solvents, or a combination of bothtypes of aprotic solvents. These (ii) organic solvents are also definedbelow.

In general, for all organic solvents useful in the (c) organic solventmedium, both (i) and (ii) types, each has a boiling point at atmosphericpressure of at least 100° C. and up to but less than 500° C., or atleast 135° C. and up to and including 350° C., or up to and including250° C.

In some embodiments, the useful (i) hydroxylic solvent is an alcoholhaving an α-hydrogen atom. Accordingly, primary and secondary alcoholsare useful and they can be monohydric or polyhydric. While eithersaturated or unsaturated alcohols can be used, it is desirable that thealcohol used be free from olefinic unsaturation. Suitable alcohols canbe of either straight-chain or branched-chain configuration, and cancontain in their structure either or both of alicyclic or aromaticcarbon-to-carbon moieties. Representative examples of suitablestraight-chain primary alcohols include but are not limited to, ethanol,n-propanol, n-butanol, n-pentanol, n-hexanol, 1-octanol,2-ethyl-1-hexanol, n-decanol, ethylene glycol, propylene glycol, andbenzyl alcohol. Representative examples of branched-chain alcoholsinclude isobutyl alcohol, isoamyl alcohol, and secondary butyl carbinol.Secondary alcohols have greater reactivity. Representative examples ofsecondary alcohols include but are not limited to, isopropyl alcohol,secondary butyl alcohol, secondary amyl alcohol, diethyl carbinol,methyl isobutyl carbinol, methyl-3-heptanol, diisobutyl carbinol,dodecanol-Z, methyl allyl carbinol, cyclohexanol, methyl cyclohexylcarbinol, phenyl methyl carbinol, and similar materials. Combinations ofany of these alcohols can be used if desired. Such materials can bereadily purchased from various commercial sources or readily preparedusing known starting materials, conditions, and reaction schemes.

Glycol ethers with both an ether and alcohol functional group in thesame molecule are also useful in practice of the present invention.Representative examples of such glycol ethers include but are notlimited to, 2-methoxyethanol, 2-ethoxyethanol, diethylene glycolmonoethyl ether (carbitol), and methoxy isopropanol. Mixtures of thesecompounds can be used if desired. Such glycol ethers are commerciallyavailable.

In many embodiments, in addition to the (i) hydroxylic organicsolvent(s), the organic solvent medium further contains one or more (ii)nitrile-containing aprotic solvents, one or more carbonate-containingaprotic solvents, or a mixture of one or more of both types of aproticsolvents.

Representative useful (ii) nitrile-containing aprotic solvents orcarbonate-containing aprotic solvents include but are not limited to,benzonitrile, butyronitrile, propylene carbonate, ethylene carbonate,propionitrile, isovaleronitrile, or valeronitrile, or a combination ofsuch compounds.

The relative volume amounts of each type of organic solvent in theoriginal (c) organic solvent medium can vary widely. Thenitrile-containing aprotic solvents or carbonate-containing aproticsolvents can be absent in some embodiments, but when present, the weightratio of the total (ii) defined aprotic solvents to the total (i)hydroxylic solvents can be from 0.1:1 to and including 0.5:1.

Non-Aqueous Silver Nanoparticle-Containing Compositions

The reducible silver ions in the non-aqueous silver precursorcomposition according to the present invention can be converted itsilver nanoparticles to provide a corresponding non-aqueous silvernanoparticle-containing composition. Details about such conversion areprovided below.

(e) Carbon Black:

As described below, (e) carbon black can be added to the non-aqueoussilver nanoparticle-containing compositions at a suitable time. Carbonblack can be obtained commercially in various forms. The (e) carbonblack can be added so that it is present it is presence in an amount ofat least 5 weight %, based on (or relative to) the total weight of theone or more (a) polymers. Typically, the amount of (e) carbon black isat least 5 weight % and up to and including 50 weight %, or moretypically in an amount of at least 5 weight % and up to and including 25weight %, based on (or relative to) the total weight of the one or more(a) polymers.

The steady shear measurements of the non-aqueous silvernanoparticle-containing compositions prepared according to the presentinvention can be performed by subjecting a composition sample to asteady shear at a constant shear rate (γ•) resulting in a generation ofa shear stress (τ). The corresponding shear stress (τ) on the sample wasmeasured using a torque transducer. The viscosity (η) was measured asfunction of the steady shear rate2(γ•) and is defined as:η=τ/γ•

Solutions of one or more (a) polymers typically exhibit a zero shearviscosity, η_(o), that is typified by constant viscosity (Newtonianregion) at low shear rates and a decrease in viscosity (shear thinning)at high shear rates. Accordingly, useful non-aqueous silvernanoparticle-containing compositions prepared according to the presentinvention exhibit Newtonian behavior at low shear rate and exhibit a lowslope of viscosity vs. shear rate <1 in the shear thinning region athigher shear rates. A fit of the Carreau model to the non-Newtoniansteady-shear data provides parameters that characterize the rheology ofthese compositions, as follows:

Carreau Equation:

$\eta = {\eta_{o}\left\lbrack {1 + \left( {\lambda\;\gamma} \right)^{a}} \right\rbrack}^{\frac{n - 1}{a}}$wherein:

-   -   η_(o) is the zero-shear viscosity that becomes constant at low        shear rates;    -   a is the exponent that defines the shape of the transition from        the zero-shear viscosity to the shear thinning or power law        region;    -   n is the parameter defining the slope in the power law region;    -   λ is a time constant for the fluid that relates to its        relaxation time; and    -   γ is shear rate.

The non-aqueous silver nanoparticle-containing compositions preparedaccording to the present inventions exhibit different solutionproperties depending upon the organic solvent medium and the functionalgroup(s) used to substitute the hydroxyl group(s) on a cellulose chain.Since solution to gel transitions have been observed in variouscellulosic polymers, forming mostly physical gel systems, it isimportant to characterize the dynamic viscoelastic behavior of thecompositions described herein. Dynamic mechanical analysis (DMA) wasused for determination of gel formation. Compositions that form gel incertain organic solvents are not useful in the practice of the presentinvention.

Measuring dynamic viscoelastic behavior involves the application of asinusoidally varying strain γ=γ_(o) sin(et) in the linear viscoelastic(LVE) region. The symbol ω is the frequency of oscillations and γ_(o) isthe strain amplitude. The shear stress (τ) generated is also sinusoidalin nature given by the expression:τ=τ_(o) sin(ωt+δ).Expanding the above expression results in two components for the stress,one in phase and one out of phase with the strain:τ=τ_(o) cos(δ)sin(ωt)+τ_(o) sin(δ)cos(ωt)The elastic or storage modulus, G′, is related to the stress componentin phase with the strain and is defined as:G′=τ _(o) cos(δ)/γ_(o)While the viscous or loss modulus G″ is related to the stress componentout of phase, with the strain and is given by:G″=τ _(o) sin(δ)/γ_(o),G′ provides information on the energy stored by the sample, and G″ isrelated to the energy dissipated by the sample. Thus, for a perfectelastic system, δ=0 and G′ assumes a finite value while G″=0.Alternatively, for a purely viscous system, δ=90° with G″ having afinite value with G′=0. Most materials (for example, polymer melts)exhibit both elastic and viscous properties and are referred to asviscoelastic materials. Therefore, for viscoelastic materials, both G′and G″ will have non-zero values. Plots of G′ and G″ as a function offrequency provide information regarding the structure of a materialbeing evaluated. For a liquid sample, G′ and G″ have slopes close to 2and 1, respectively, on a log-log plot of modulus vs. frequency at lowfrequencies that are defined as their terminal slopes in the flowregion.

At low frequencies, Tan δ, is defined as the ratio of G″/G′ that ismeasured at a given frequency. Tan δ is >1, when the sample exhibitsmostly viscous characteristics and Tan δ that is <1 is dominated byelastic behavior. The point of intersection of G′ and G″ (overlapfrequency) provides information on the relaxation time. As an elasticnetwork is formed, the slopes of both G′ and G″ decrease to a pointwhere G′ is parallel but just below G″ and both slopes are equal to 0.6,which is defined as the gel point or point where a connective networkhas spanned the entire sample. As the network increases, G′ dominates G″and Tan δ becomes <1. For an elastic gel network, both moduli exhibitfrequency independent behavior and G′ is significantly larger than G″.For a dynamic frequency analysis to be valid, the experiments have to beconducted within the LVE region.

Each of the non-aqueous silver nanoparticle-containing compositionsprepared according to the present inventions exhibits a viscoelasticresponse, Tan δ value, of at least 15, or typically at least 30, or evenat least 40, and up to and including 150, all measured at 25° C., usingan Anton Paar MCR 501 rheometer and couette geometry at a frequency of10 radians/sec (see for example, Ferry, J., “Viscoelastic Properties ofPolymers”, Wiley and Sons, New York, 1961).

Precursor Articles

The non-aqueous silver precursor compositions according to the presentinvention can be used to provide “precursor” articles that can then beused in various operations to provide electrically-conductivemetal-containing thin layers or electrically-conductive metal-containingpatterns in various “product articles” as described below.

As used herein, the term “precursor article” refers to an article (orelement) typically designed to have a substrate having thereon a drylayer or dry pattern comprising a silver nanoparticle-containingcomposition and thus, are articles in which silver ion reduction to (d)silver nanoparticles has already occurred and there are no appreciableamounts of (b) reducible silver ions, that is they are generally presentin an amount of less than 5 mol %, based on the total amount of silverin the corresponding silver nanoparticle-containing composition.

Thus, each of the precursor articles according to the present inventioncomprises a substrate (described below), and has disposed on at leastone supporting surface thereof a pattern of a dry silvernanoparticle-containing composition comprising:

at least 20 weight %, or at least 50 weight %, and up to and including90 weight %, or up to and including 99.9 weight %, all based on thetotal weight of the pattern of the dry silver nanoparticle-containingcomposition, of one or more (a) polymers selected from one or more ofcellulose acetate, cellulose acetate phthalate, cellulose acetatebutyrate, cellulose acetate propionate, cellulose acetate trimellitate,hydroxypropylmethyl cellulose phthalate, methyl cellulose, ethylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose,hydroxypropylmethyl cellulose, and carboxymethyl cellulose;

(d) silver nanoparticles having a mean particle size of at least 25 nmand up to and including 750 nm, or of at least 50 nm and up to andincluding 500 nm, or even of at least 50 nm and up to and including 300nm; and

(e) carbon black in an amount of up to and including 50 weight %, or atleast 5 weight % and up to and including 50 weight %, or even at least 5weight % and up to and including 25 weight %, all based on (or relativeto) the total weight of the one or more (a) polymers;

less than 5 mol % of (b) reducible silver ions, or less than 2 mol %, oreven less than 1 mol %, all based on the total molar amount of silver inthe pattern of the dry silver nanoparticle-containing composition;

wherein the (d) silver nanoparticles are present in the pattern in someembodiments in an amount of at least 0.1 weight % and up to andincluding 400 weight %, or at least 15 weight % and up to and including200 weight %; and in other embodiments, in an amount of at least 0.1weight % and up to and including 5 weight %, or at least 0.25 weight %and up to and including 4 weight %, all based on (or relative to) thetotal weight of the one or more (a) polymers.

When one or more patterns of the dry silver nanoparticle-containingcomposition are formed on the substrate, in some embodiments, at leastone of the patterns can comprise a combination of fine lines, each fineline having an average dry width of at least 1 μm and up to andincluding 20 μm, which combination of fine lines can be arranged inparallel, crossing at any desired angle, a combination thereof, or in arandom arrangement. In other words, each pattern can be designed to haveany predetermined grid pattern that can be achieved in the art.

The presence of the (e) carbon black in the silvernanoparticle-containing composition (and resulting patterns) isparticularly advantageous when the substrate (described in detail below)is transparent, such as a transparent continuous polymeric film forexample a transparent continuous polycarbonate, polystyrene, orpolyester film.

In many embodiments of “precursor” articles, the substrate has a firstsupporting surface and a second opposing supporting surface, and one ormore dry patterns of the silver nanoparticle-containing composition aredisposed on the first supporting surface, and optionally, one or moredry patterns of the same or different silver nanoparticle-containingcomposition are disposed on the second opposing supporting surface. Thedry patterns can be disposed on the two opposing supporting surfaces inany opposing arrangement, that is either directly opposite one another,or offset in some desired arrangement.

For example, in some embodiments of the article, the substrate is atransparent continuous polyester film that has a first supportingsurface and a second opposing supporting surface,

the article further comprising multiple (two or more) individual drypatterns formed on the first supporting surface which dry patterscomprise the same or different silver nanoparticle-containingcompositions, and further comprising multiple (two or more) individualdry patterns formed on the second opposing supporting surface whichopposing multiple dry patterns comprise the same or different silvernanoparticle-containing compositions.

For example, in such embodiments, all of the multiple individual drypatterns on both the first supporting surface and the second opposingsupporting surface can comprise the same silver nanoparticle-containingcomposition, the (d) silver nanoparticles in each individual dry patternhaving a mean particle size of at least 50 nm and up to and including300 nm, and each of the multiple individual dry patterns comprises finelines having an average dry width of at least 1 μm and up to andincluding 20 μm.

As used herein, the term “product” article refers to an article (orelement) in which an electrolessly plated copper pattern has been formedor disposed solely on the corresponding pattern of a silvernanoparticle-containing composition as described above. Thus, each ofsuch product articles according to the present invention is derived froma “precursor” article according to the present invention, and comprisesa substrate as described below (for example a transparent substrate ofsome type), and has disposed on a supporting surface thereof a patternof electrolessly plated copper that is disposed solely on acorresponding pattern of a dry silver nanoparticle-containingcomposition as described above, comprising:

at least 20 weight % or at least 50 weight % and up to and including 90weight %, or up to and including 99.9 weight %, of one or more (a)polymers as described above, all based on the total weight of thecorresponding pattern of the dry silver nanoparticle-containingcomposition;

(d) silver nanoparticles having a mean particle size of at least 25 nmand up to and including 750 nm, or of at least 50 nm and up to andincluding 500 nm, or even of at least 50 nm and up to and including 300nm; and

(e) carbon black in an amount of up to and including 50 weight % (or atleast 5 weight % and up to and including 50 weight %, or at least 5weight % and up to and including 25 weight %), all based on (or relativeto) the total weight of the one or more (a) polymers;

less than 5 mol % of (b) reducible silver ions, or less than 2 mol %, oreven less than 1 mol %, all based on the total molar amount of silver inthe pattern of the dry silver nanoparticle-containing composition;

wherein the (d) silver nanoparticles are present in the pattern in someembodiments in an amount of at least 0.1 weight % and up to andincluding 400 weight %, or at least 15 weight % and up to and including200 weight %; and in other embodiments, in an amount of at least 0.1weight % and up to and including 5 weight %, or at least 0.25 weight %and up to and including 4 weight %, all based on (or relative to) thetotal weight of the one or more (a) polymers.

In many product articles according to this invention, the pattern ofelectrolessly plated copper comprises a combination of fine lines, eachfine line having an average dry width of at least 1 μm and up to andincluding 20 μm, which combination of fine lines can be arranged inparallel, crossing at any desired angle, a combination thereof, or in arandom arrangement. In other words, each pattern can be designed to haveany predetermined grid pattern that can be achieved in the art.

In some embodiments of product articles, the substrate has a firstsupporting surface and a second opposing supporting surface, and one ormore patterns of electrolessly plated copper are disposed on the firstsupporting surface, and optionally, one or more patterns of electrolessplated copper are disposed on the second opposing supporting surface.

Moreover, the substrate can be a transparent continuous polyester filmthat has a first supporting surface and a second opposing supportingsurface, and the product article further comprises multiple (two ormore) individual patterns of electrolessly plated copper formed on thefirst supporting surface, and further comprising multiple (two or more)individual patterns of electrolessly plated copper formed on the secondopposing supporting surface.

For example, in such product articles, all of the multiple individualpatterns of electrolessly plated copper on both the first supportingsurface and the second opposing supporting surface can be formed on thesame corresponding silver nanoparticle-containing composition, the (d)silver nanoparticles in each individual pattern of electrolessly platedcopper having a mean particle size of at least 50 nm and up to andincluding 300 nm, and each of the multiple individual patterns ofelectrolessly plated copper comprising fine lines having an average drywidth of at least 1 μm and up to and including 20 μm.

Both precursor articles and product articles described herein comprise asuitable substrate that generally has two planar surfaces: a firstsupporting side (or surface) and a second opposing supporting side (orsurface). Such substrates can have any suitable form such as sheets ofany desirable size and shape, webs of metals, films, and elongatedfibers or woven fibers (such as in webs of textiles) or other porousmaterials, and especially continuous webs of various transparent,translucent, or opaque polymeric materials (such as polycarbonates andpolyesters) that can be supplied, used, or stored as rolls.

More specifically, a uniform thin film or one or more thin film patternsof the silver nanoparticle-containing composition are provided in asuitable manner on one or more supporting (planar) sides of a suitablesubstrate to provide a precursor article as described according to themethod described below. Typically, such precursor articles have aninitially “wet” organic solvent-based layer or pattern during andimmediately after application to the substrate but the organic solventmedium can be removed as described below to provide the desired uniformthin film layer or one or more thin film patterns.

Suitable substrates can be composed of any suitable material as long asit does not inhibit the purpose of the present invention to formelectrolessly plated copper or other metal patterns. For example,substrates can be formed from materials including but are not limitedto, polymeric films, metals, glasses (untreated or treated for examplewith tetrafluorocarbon plasma, hydrophobic fluorine, or a siloxanewater-repellant material), silicon or ceramic materials such as ceramicwafers, fabrics, papers, and combinations thereof (such as laminates ofvarious films, or laminates of papers and films) provided that a uniformthin film or thin film pattern can be formed thereon in a suitablemanner and followed by thermal treatment (heating) on at least onesupporting surface thereof. The substrate can be transparent,translucent, or opaque, and rigid or flexible. The substrate can includeone or more auxiliary polymeric or non-polymeric layers or one or morepatterns of other materials before the non-aqueous silvernanoparticle-containing composition is applied according to the presentinvention.

More specifically, suitable substrate materials for forming precursorand product articles according to the present invention include but arenot limited to, metallic films or foils, metallic films on polymer,glass, or ceramic materials, metallic films on electrically conductivefilm supports, semi-conducting organic or inorganic films, organic orinorganic dielectric films, or laminates of two or more layers of suchmaterials. Useful substrates can include transparent polymeric filmssuch as poly(ethylene terephthalate) films, poly(ethylene naphthalate)films, polyimide films, polycarbonate films, polyacrylate films,polystyrene films, polyolefin films, and polyamide films, silicon andother ceramic materials, metal foils such as aluminum foils, cellulosicpapers or resin-coated or glass-coated papers, glass or glass-containingcomposites, metals such as aluminum, tin, and copper, and metalizedfilms. Porous fabrics, glasses, and polymeric webs can also be used.

Particularly useful substrates including continuous flexible polymericfilms, metal foils, and textile webs. Useful continuous flexiblepolymers films include transparent continuous polymeric films such astransparent continuous polyester films such as films of poly(ethyleneterephthalate), polycarbonate films, or poly(vinylidene chloride) filmswith or without surface-treatments or coatings as noted below.

For example, either or both supporting surfaces of the substrate can betreated with a primer layer or electrical or mechanical treatments (suchas graining) to render that surface “receptive” and improve adhesion ofthe silver nanoparticle-containing composition and resultingelectrolessly plated copper or other metal. An adhesive layer can havevarious properties in response to stimuli (for example, it can bethermally activated, solvent activated, or chemically activated). Usefuladhesive materials of this type are described for example in [0057] ofU.S. Patent Application 2008/0233280 (Blanchet et al.), the disclosureof which is incorporated herein by reference. A separate receptive layercan have any suitable dry thickness of at least 0.05 μm when measured at25° C.

The two (planar) supporting surfaces of the substrate, especiallypolymeric substrates, can be treated by exposure to corona discharge,mechanical abrasion, flame treatments, or oxygen plasmas, or coated withvarious polymeric films, such as poly(vinylidene chloride) or anaromatic polysiloxane as described for example in U.S. Pat. No.5,492,730 (Balaba et al.) and U.S. Pat. No. 5,527,562 (Balaba et al.)and U.S. Patent Application Publication 2009/0076217 (Gommans et al.),the disclosures of all of which are incorporated herein by reference.

Useful substrates can have a desired dry thickness depending upon theeventual use of the precursor and product articles. For example, thesubstrate dry thickness (including all treatments and auxiliary layers)can be at least 0.001 mm and up to and including 10 mm, and especiallyfor transparent polymeric films, the substrate dry thickness can be atleast 0.008 mm and up to and including 0.2 mm.

The substrate used in the precursor and product articles describedherein can be provided in various forms, such as for example, individualsheets of any size or shape, and continuous webs such as continuous websof transparent substrates (including transparent continuous polyesterfilms) that are suitable for roll-to-roll operations. Such continuouswebs can be divided or formed into individual first, second, andadditional portions on a first supporting surface and a second opposingsupporting surface on which can formed the same or differentcorresponding silver nanoparticle-containing patterns in the different(or individual) portions of a supporting side (such as the firstsupporting sides) as well as the same or different electrolessly platedcopper thin film patterns formed on the corresponding silvernanoparticle-containing patterns.

In many useful embodiments, the substrate is a continuous transparentflexible polymeric film, a metal foil, or a textile web that can be usedin various continuous manufacturing operations.

Forming Silver Nanoparticles and Silver Nanoparticle Patterns

Articles are prepared according to the present invention using (d)silver nanoparticles produced by subjecting a non-aqueous silverprecursor composition according to this invention (details describedabove) to a temperature of at least 20° C. for a time sufficient toconvert at least 90 mol % of the (b) reducible silver ions to silvermetal in the form of (d) silver nanoparticles having a mean particlesize of at least 25 nm and up to and including 750 nm, thereby forming anon-aqueous silver nanoparticle-containing composition. In mostembodiments, conversion of at least 95 mol % of the (b) reducible silverions, or of at least 98 mol % of the (b) reducible silver ions, to (d)silver nanoparticles is possible.

In some embodiments, (b) reducible silver ions can be present in thenon-aqueous silver precursor composition in an amount of at least 0.1weight % and up to and including 5 weight %, or at least 0.25 weight %and up to and including 4 weight %, based on (or relative to) the totalweight of the one or more (a) polymers, and such compositions areparticularly useful for providing larger or solid areas in an appliedpattern on a substrate.

Alternatively, (b) reducible silver ions can be present in thenon-aqueous silver precursor composition in an amount of at least 0.1weight % and up to and including 400 weight %, or at least 15 weight %and up to and including 200 weight %, based on (or relative to) thetotal weight of the one or more (a) polymers. Such compositions areparticularly useful for printing fine lines in an applied pattern on asubstrate.

Typically, reduction of (b) reducible silver ions to (d) silvernanoparticles can be carried out by mixing one or more cellulosicpolymers as described above in an (c) organic solvent medium comprisingat least one or more (i) hydroxylic solvents (and optionally one or more(ii) aprotic solvents) as defined above, with stirring at a temperatureof at least 20° C. to obtain a non-aqueous polymer solution comprisingthe one or more cellulosic polymers in the organic solvent medium. Asource of (b) reducible silver ions, such as a silver salt or silvercomplex as described above is then added to the non-aqueous polymersolution at a suitable temperature and the resulting non-aqueous silverprecursor composition is then stirred at 20° C. or higher for up to 48hours to reduce the (b) reducible silver ions. It is particularly usefulto expedite silver ion reduction by heating the non-aqueous silverprecursor composition at a temperature of at least 500 and up to andincluding 100° C. for at least 1 minute and up to and including 1 hour,using a heating mantle or an oil bath.

After or during this silver ion reduction process, one or more (ii)nitrile-containing aprotic solvents, carbonate-containing aproticsolvents, or both types of aprotic solvents, can be added to thenon-aqueous silver nanoparticle-containing composition (silver ionreduction may not be complete at this point). The amounts added can besufficient to provide a desired 9:1 volume ratio of (i) hydroxylicorganic solvents to (ii) aprotic organic solvents in the overall (c)organic solvent medium. Typically, the non-aqueous silvernanoparticle-containing composition is cooled sufficiently for this (ii)aprotic solvent addition. As noted above, some of the aprotic solventscan be present in the original (c) organic solvent medium.

If carbon black is to be included in the non-aqueous silvernanoparticle-containing composition, it can be added at this point,typically at room temperature at the appropriate amounts described above(at least 5 weight % and up to and including 50 weight %, based on thetotal amount of the one or more (a) polymers), using a suitable mixingmeans such as a shear mixer. For example, suitable shear mixers arecommercially available from various sources such as Silverson, Admix,and Ross, for suitable dispersion of the carbon black particles withinthe non-aqueous silver nanoparticle-containing composition.

The non-aqueous silver nanoparticle-containing composition is thendisposed onto one or more supporting surfaces of a substrate (as definedabove) to provide, upon drying, either a thin uniform film, or one ormore patterns of the non-aqueous silver nanoparticle-containingcomposition. Disposition of the non-aqueous silvernanoparticle-containing composition can be achieved in a variety ofmeans known in the art for applying solutions or dispersions to a solidsubstrate.

For example, in some embodiments, a non-aqueous silvernanoparticle-containing composition according to the present inventioncan be disposed in a uniform or patternwise manner onto one or bothsupporting sides of the substrate as defined above. For example, avariety of films, including polymeric films composed of polyethylene,polypropylene, biaxially oriented polypropylene, polyethyleneterephthalate, polybutylene terephthalate and polyamide, can be utilizedas suitable transparent substrates. The choice of substrate structure isnot, however, limited to films but includes any material that can beformed into bags, shrink wrap, plates, cartons, boxes, bottles, crates,and other containers. The non-aqueous silver nanoparticle-containingcomposition deposition or application can be carried out for example,using uniform inkjet printing or using a blade coating, gap coating,slot die coating, X-slide hopper coating, or knife on roll operations.

The non-aqueous silver nanoparticle-containing composition can bedisposed on the substrate (one or both supporting surfaces) in apatternwise manner using techniques described below such as flexographicprinting, screen printing, or inkjet printing to provide one or moresilver nanoparticle-containing patterns on the substrate.

Any applied pattern of non-aqueous silver nanoparticle-containingcomposition can comprise a grid of fine lines (or other shapes includingcircles or an irregular network) as described above and the optimal drythickness (or width) can be tailored for an intended use.

In some embodiments, the same or different silvernanoparticle-containing pattern can be provided in a suitable manner indifferent portions on both the first supporting surface and the secondopposing supporting surface of the substrate to form a “duplex” ordual-sided precursor article, and such patterns can be provided usingthe same or different non-aqueous silver nanoparticle-containingcomposition.

In many embodiments, a non-aqueous silver nanoparticle-containingcomposition can be applied on one or both supporting surfaces of thesubstrate (for example as a roll-to-roll web) using flexographicprinting with an elastomeric relief element such as those derived fromflexographic printing plate precursors, many of which are known in theart. Some such precursors are commercially available, for example as theCYREL® Flexographic Photopolymer Plates from DuPont and the Flexcel SRand NX Flexographic plates from Eastman Kodak Company.

Useful elastomeric relief elements are derived from flexographicprinting plate precursors and flexographic printing sleeve precursors,each of which can be appropriately imaged (and processed if needed) toprovide the elastomeric relief elements for “printing” suitable silvernanoparticle-containing patterns. Useful precursors of this type aredescribed for example, in U.S. Pat. No. 7,799,504 (Zwadlo et al.) andU.S. Pat. No. 8,142,987 (Ali et al.) and U.S. Patent ApplicationPublication 2012/0237871 (Zwadlo), the disclosures of all of which areincorporated herein by reference. Such flexographic printing precursorscan comprise elastomeric photopolymerizable layers that can be imagedthrough a suitable mask image to provide an elastomeric relief element(flexographic printing plate or flexographic printing sleeve). Theresulting relief layer can be same or different depending upon whetherthe same or different patterns of non-aqueous silvernanoparticle-containing compositions are to be formed on one or bothsupporting surfaces of the substrate.

In other embodiments, an elastomeric relief element can be provided froma direct (or ablation) laser-engraveable elastomer relief elementprecursor, with or without integral masks, as described for example inU.S. Pat. No. 5,719,009 (Fan), U.S. Pat. No. 5,798,202 (Cushner et al.),U.S. Pat. No. 5,804,353 (Cushner et al.), U.S. Pat. No. 6,090,529(Gelbart), U.S. Pat. No. 6,159,659 (Gelbart), U.S. Pat. No. 6,511,784(Hiller et al.), U.S. Pat. No. 7,811,744 (Figov), U.S. Pat. No.7,947,426 (Figov et al.), U.S. Pat. No. 8,114,572 (Landry-Coltrain etal.), U.S. Pat. No. 8,153,347 (Veres et al.), U.S. Pat. No. 8,187,793(Regan et al.), and U.S. Patent Application Publications 2002/0136969(Hiller et al.), 2003/0129530 (Leinenback et al.), 2003/0136285 (Telseret al.), 2003/0180636 (Kanga et al.), and 2012/0240802 (Landry-Coltrainet al.), the disclosures of all of which are incorporated herein byreference.

When the noted elastomeric relief elements are used to provide patterns,the non-aqueous silver nanoparticle-containing composition can beapplied in a suitable manner to the uppermost relief surface (raisedsurface) in the elastomeric relief element. Then, application to asubstrate can be accomplished in a suitable procedure while as little aspossible is coated from the sides (slopes) or recesses of the reliefdepressions. Anilox roller systems or other roller application systems,especially low volume Anilox rollers, below 2.5 billion cubicmicrometers per square inch (6.35 billion cubic micrometers per squarecentimeter) and associated skive knives can be used. In suchembodiments, the non-aqueous silver nanoparticle-containing compositioncan be designed to have optimal viscosity for flexographic printing.When a substrate is moved through the roll-to-roll handling system froma flexographic printing plate cylinder to an impression cylinder, theimpression cylinder applies pressure to the flexographic printing platecylinder that transfers an image from an elastomeric relief element tothe substrate in forming a precursor article according to the presentinvention.

Each precursor article can be “printed” one or more times using inkjetprinting, screen printing, or flexographic printing as a web (forexample, a roll-to-roll continuous web) that can contain multiplepatterns (or individual precursor articles after cutting) in multipleportions of the continuous web that is passed through various stations.The same or different silver nanoparticle-containing compositions can beapplied (for example, printed) on one or both supporting surfaces of thesubstrate in the continuous roll-to-roll production operation. In manyembodiments, different patterns of silver nanoparticle-containingcompositions can be formed on each supporting surface.

After deposition of the non-aqueous silver nanoparticle-containingcomposition onto the substrate, for example, in a patternwise manner, atleast 75 weight % and up to and including 100 weight % of the original(c) solvent medium (described above) and any added (ii)nitrile-containing aprotic solvent or carbonate-containing aproticsolvent can be removed in any suitable manner to form a precursorarticle. For example, ambient drying can be carried out in an openenvironment, or the article with applied composition(s) can be subjectto “active” drying operations and apparatus (for example, heated dryingchamber). Useful drying conditions can be as low as room temperature foras little as 5 seconds and up to and including several hours dependingupon the manufacturing process. In many processes, such as roll-to-rollmanufacturing operations, drying conditions can be employed at anysuitable temperature, for example greater than 50° C. to remove at least75 weight % and up to 100 weight % of all remaining organic solventswithin at least 1 second and up to and including 10 seconds or evenwithin 5 seconds.

Thus, as described above, the non-aqueous silver nanoparticle-containingcomposition can be disposed onto a supporting surface of the substratein a patternwise manner, for example, using inkjet printing, screenprinting, or flexographic printing, to form a silvernanoparticle-containing pattern.

Forming Product Articles

The resulting precursor article described above can be converted to aproduct article by electrolessly plating a suitable metal onto thecorresponding silver nanoparticle-containing pattern to form acorresponding electrically-conductive metal (for example, copper)pattern on the silver nanoparticle-containing pattern. Thus, the silvernanoparticles in the corresponding pattern act as electroless seed metalparticles (catalyst) for the metal electroless plating.

The precursor article can be stored for an indeterminate period of timebefore metal electroless plating is carried out, but in many embodimentsof continuous manufacturing operations (such as roll-to-rolloperations), the precursor article is immediately immersed in a suitableaqueous-based electroless metal plating bath or solution.

For example, the precursor article containing catalytic silvernanoparticles in the silver nanoparticle-containing pattern(s) can becontacted with an electroless plating metal that is the same as ordifferent from the catalytic electroless seed silver nanoparticles. Inmost embodiments, the electroless plating metal is a different fromsilver.

Any metal that will likely electrolessly “plate” on the catalyticelectroless seed silver nanoparticles can be used at this point, but inmost embodiments, the electroless plating metal can be for examplecopper(II), gold(IV), palladium(II), platinum(II), nickel(II),chromium(II), and combinations thereof. Copper(II), nickel (II),platinum(II), and palladium(II) are particularly useful electrolessplating metals. The one or more electroless plating metals can bepresent in the aqueous-based electroless plating bath or solution in anamount of at least 0.01 weight % and up to and including 20 weight %based on total solution weight. Electroless plating can be carried outusing known temperature and time conditions, as such conditions are wellknown in various textbooks and scientific literature. It is also knownto include various additives such as metal complexing agents orstabilizing agents in the aqueous-based electroless plating solutions.Variations in time and temperature can be used to change the metalelectroless plating thickness or the metal electroless platingdeposition rate.

A useful aqueous-based electroless plating solution or bath is anelectroless copper(II) plating bath that contains formaldehyde as areducing agent. Ethylenediaminetetraacetic acid (EDTA) or salts thereofcan be present as a copper complexing agent. For example, copperelectroless plating can be carried out at room temperature for severalseconds and up to several hours depending upon the desired depositionrate and plating rate and plating metal thickness.

Other useful aqueous-based electroless plating solutions or bathscomprise copper(II) with EDTA and dimethylamineborane, copper(II) withcitrate and hypophosphite, nickel(II) with lactic acid, acetic acid, anda hypophosphite, and other industry standard aqueous-based electrolessbaths or solutions such as those described by Mallory et al. inElectroless Plating: Fundamentals and Applications 1990.

After the electroless plating procedure, the resulting product articlecan be removed from the aqueous-based electroless plating bath orsolution and washed using distilled water or deionized water or anotheraqueous-based solution to remove any residual electroless platingchemistry.

To change the surface of the electroless plated metal for visual ordurability reasons, it is possible that a variety of post-treatments canbe employed including surface plating of still at least another (thirdor more) metal such as nickel or silver on the electrolessly platedmetal (this procedure is sometimes known as “capping”), or the creationof a metal oxide, metal sulfide, or a metal selenide layer that isadequate to change the surface color and scattering properties withoutreducing the conductivity of the electrolessly plated (second) metal.

As one skilled in the art should appreciate, the individual silvernanoparticle deposition and electroless plating features described abovecan be carried out two or more times before proceeding to the nextprocedure or step. For example, multiple depositions of a non-aqueoussilver nanoparticle-containing composition can be carried out to providemore catalytic metal followed by multiple electroless platingtreatments. Sequential washing or rinsing steps can also be carried outwhere appropriate.

The cumulative result of the described features and operations is aproduct article as described above comprising the substrate (forexample, individual sheets or a continuous web) having one or moreelectrically-conductive metal-containing thin film patterns on one orboth supporting surfaces of the substrate.

The one or more electrolessly plated and electrically-conductive metalpatterns formed in the product article can be further “processed” oroperated on in various manufacturing operations to incorporate them,individually or in combination, into various devices including but notlimited to touch screens or other display devices that can be used innumerous industrial, consumer, and commercial products.

Systems and methods of fabricating flexible and optically complianttouch sensors in a high-volume roll-to-roll manufacturing processwherein micro electrically-conductive features can be created in asingle pass are possible using the present invention. The ink jettableor flexographic printable non-aqueous silver nanoparticle-containingcompositions according to the present invention can be used to preparesuch systems and methods with one or more ink jet printing devices orone or more flexographic printing members to form multiple highresolution electrically-conductive images or patterns after electrolessplating.

In other embodiments, the present invention can be used to generateelectrically-conductive metal patterns and electrodes within devices,including but not limited to, membrane touch switch (MTS), batterytesters, biomedical, electroluminescent lamps, radio frequencyidentification (RFID) antenna, flat panel displays such as plasmadisplay panel (PDP) and organic light emitting diode (OLED) display,printed transistors and circuits, thin film photovoltaics, and otherdevices that would be readily apparent to one skilled in the art. Inother words, such product articles according to this invention can bedevices themselves rather than articles that are incorporated into adevice. Alternatively, the product articles are devices into which otherproduct articles are incorporated.

The present invention provides at least the following embodiments andcombinations thereof, but other combinations of features are consideredto be within the present invention as a skilled artisan would appreciatefrom the teaching of this disclosure:

1. An article comprising a substrate, and having disposed on asupporting surface thereof, a pattern of a dry silvernanoparticle-containing composition comprising:

at least 20 weight % of one or more (a) polymers, based on the totalweight of the pattern, which one or more (a) polymers are selected fromone or more of cellulose acetate, cellulose acetate phthalate, celluloseacetate butyrate, cellulose acetate propionate, cellulose acetatetrimellitate, hydroxypropylmethyl cellulose phthalate, methyl cellulose,ethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose,hydroxypropylmethyl cellulose, and carboxymethyl cellulose;

(d) silver nanoparticles having a mean particle size of at least 25 nmand up to and including 750 nm, that are present in the pattern in anamount of at least 0.1 weight % and up to and including 400 weight %,based on the total weight of the one or more (a) polymers;

(e) carbon black in an amount of at least 5 weight % and up to andincluding 50 weight %, based on the total weight of the one or more (a)polymers; and

less than 5 mol % of (b) reducible silver ions, based on the total molaramount of silver in the dry silver nanoparticle-containing composition.

2. The article of embodiment 1, wherein the (d) silver nanoparticleshave a mean particle size of at least 50 nm and up to and including 300nm.

3. The article of embodiment 1 or 2, wherein the (d) silvernanoparticles are present in an amount of at least 0.1 weight % and upto and including 5 weight %, based on the total weight of the one ormore (a) polymers.

4. The article of any of embodiments 1 to 3, wherein the (d) silvernanoparticles are present in an amount of at least 15 weight % and up toand including 200 weight %, based on the total weight of the one or more(a) polymers.

5. The article of any of embodiments 1 to 4, wherein the substrate is acontinuous flexible polymeric film, a metal foil, or a textile web.

6. The article of any of embodiments 1 to 5, wherein the substrate is atransparent continuous polymeric film.

7. The article of any of embodiments 1 to 6, wherein the one or more (a)polymers comprise one or more of carboxymethyl cellulose, celluloseacetate butyrate, cellulose acetate propionate, cellulose acetate, andhydroxypropyl cellulose.

8. The article of any of embodiments 1 to 7, wherein the pattern of thedry silver nanoparticle-containing composition comprises a combinationof fine lines, each fine line having an average dry width of at least0.1 μm and up to and including 20 μm, which combination of fine linescan be arranged in parallel, crossing at any desired angle, acombination thereof; or in a random arrangement.

9. The article of any of embodiments 1 to 8, wherein the substrate has afirst supporting surface and a second opposing supporting surface, andone or more patterns of the dry silver nanoparticle-containingcomposition are disposed on the first supporting surface, andoptionally, one or more patterns of the same or different dry silvernanoparticle-containing composition is disposed on the second opposingsupporting surface.

10. The article of any of embodiments 1 to 9, wherein the substrate is atransparent continuous polyester film that has a first supportingsurface and a second opposing supporting surface,

the article further comprising multiple individual patterns formed onthe first supporting surface which one or more multiple individualpatterns comprise the same or different dry silvernanoparticle-containing compositions, and further comprising multipleopposing patterns formed on the second opposing supporting surface thatcomprise the same or different dry silver nanoparticle-containingcompositions.

11. The article of embodiment 10, wherein all of the multiple individualpatterns on both the first supporting surface and the second opposingsupporting surface comprise the same dry silver nanoparticle-containingcomposition, the (d) silver nanoparticles in each individual patternhaving a mean particle size of at least 50 nm and up to and including300 nm, and each of the multiple individual patterns comprising finelines having an average dry width of at least 0.1 μm and up to andincluding 20 μm.

12. The article of any of embodiments 1 to 11, wherein the pattern ofthe dry silver nanoparticle-containing composition further comprises atleast 5 weight % and up to and including 25 weight % of a carbon black,based on the total weight of the one or more (a) polymers.

13. The article of any of embodiments 1 to 12, further comprising apattern of electrolessly plated metal that is disposed solely on thepattern of the dry silver nanoparticle-containing composition.

14. The article of embodiment 13, wherein the substrate has a firstsupporting surface and a second opposing supporting surface, andcomprises one or more patterns of electrolessly plated metal disposed onthe first supporting surface, and optionally, one or more patterns ofelectroless plated metal disposed on the second opposing supportingsurface.

15. The article of embodiment 13 or 14, wherein the substrate is atransparent continuous polyester film that has a first supportingsurface and a second opposing supporting surface,

the article further comprising multiple individual patterns ofelectrolessly plated copper formed on the first supporting surface, andcomprising multiple individual patterns of electrolessly plated copperformed on the second opposing supporting surface.

16. The article of any of embodiments 13 to 15, wherein theelectrolessly plated metal is copper.

The following Examples are provided to illustrate the practice of thisinvention and are not meant to be limiting in any manner.

Invention Example 1: Preparation of Non-Aqueous Silver NanoparticleComposition in 2-Methoxyethanol

In a three-necked round bottomed flask, cellulose acetate (7.5 grams,Sigma Aldrich, 39.7 weight % acetyl, M_(n)˜50,000 by GPC) was dissolvedin 2-methoxyethanol (138.75 grams) as the organic solvent medium bystirring at 90° C. for 30 minutes to obtain a 5 weight % solution ofcellulose acetate in 2-methoxyethanol. The resulting solution was cooledto room temperature and silver nitrate (3.75 grams) was added whilestirring to provide reducible silver ions. The resulting non-aqueoussilver precursor composition was heated at 90-100° C. for 10-20 minutesusing a heating mantle.

An amber-colored non-aqueous silver nanoparticle-containing compositionwas obtained and slowly cooled (over 30 minutes) to room temperature,and it contained 33 weight % of silver nanoparticles with respect to theweight of cellulose acetate polymer (that was present at about 5 weight%).

An aliquot of the aforementioned amber-colored non-aqueous silvernanoparticle-containing composition was placed in a 0.1 cm cuvette and aUV-Vis absorption spectrum recorded, showing a clear plasmonic band at430 nm due to the presence of silver nanoparticles in the composition(see FIG. 1). Conversion of reducible silver ions to silvernanoparticles during the heating process was determined by CapillaryElectrophoresis to be 97.4 mol %.

Particle size distribution was measured using a dynamic light scatteringmethod (Malvern Instruments Ltd. Zetasizer Nano-ZS (ZEN) Dynamic LightScattering or QELS: Quasi-Elastic Light Scatter), and the mean silvernanoparticle particle diameter [Dv (50%)] was determined. The sizedistribution of the silver nanoparticles was bimodal with approximately35 volume % of the silver nanoparticles at 54 nm in size and 65 volume %of the silver nanoparticles at 385 (the mean silver nanoparticle sizewas 275 nm) (see FIG. 2). Upon extended keeping (30 days) at roomtemperature, the silver nanoparticle size distribution did not changeappreciably (also, see FIG. 2).

Rheology Measurement:

A sample of the non-aqueous silver nanoparticle-containing compositiondescribed above was evaluated in a MCR 501 with couette geometry at 25°C. with a frequency sweep from 100 to 1 radians/s followed by twoconsecutive steady shear runs from 1 to 10,000 l/s for the sample. Thesample was then loaded into the rheometer at 25° C. and equilibratedbefore starting a time sweep in dynamic mode to determine G′ (see FIG.3). The Tan δ of the non-aqueous silver nanoparticle-containingcomposition was determined to be 33.2.

Inventive Example 2: Flexographic Printing of Non-Aqueous SilverNanoparticle Composition

To a sample of the non-aqueous silver nanoparticle-containingcomposition of Invention Example 1, 10 weight % of propylene carbonatewas added and the composition was mixed thoroughly. Fine lines ofnominal width 7-10 μm were printed as a pattern on a supporting surfaceof a transparent poly(ethylene terephthalate) film substrate using thiscomposition as the “ink”, a flexographic test printer IGT F1, andflexographic printing members obtained from commercially available KodakFlexcel NX photopolymer plates that had been imaged using a mask thatwas written using the Kodak Square Spot laser technology at a resolutionof 12,800 dpi.

The “printed” corresponding silver nanoparticle-containing pattern wasdried by removing organic solvents at room temperature in air. Thenominal height of printed features was between 100 nm and 200 nm and thewidth of resulting fine lines was about 5-10 μm.

The resulting precursor article having a pattern of dried non-aqueoussilver nanoparticle-containing composition was immersed in anelectroless copper plating bath, ENTHONE® (Enplate LDS CU-406 SC), at45° C. for 5 minutes using conditions suggested by the commercialsupplier. The resulting product article was taken out of the electrolessplating bath, rinsed with water, and dried. A pattern of metallic copperwas seen on the surface of the corresponding silver nanoparticle patternin each product article. A micrograph of the printed and electrolesslycopper plated product article showed clear printed metallic copper linesas seen in FIG. 4. The nominal height of printed and copper platedfeatures was between 600-1200 nm and the width of the resulting copperplated fine lines was 10-15 μm.

Invention Example 3: Preparation of Non-Aqueous SilverNanoparticle-Containing Composition in 1-Methoxy-2-propanol

In a 25 ml beaker, cellulose acetate propionate (0.5 grams, Eastman CAP504-0.2) was dissolved in 1-methoxy-2-propanol (9.25 grams) by stirringat 90° C. for 30 minutes. This solution was cooled to room temperatureand silver nitrate (0.25 grams) was added while stirring to providereducible silver ions. The resulting non-aqueous silver precursorcomposition was heated at 90-110° C. for 10-20 minutes using a hotplate.

An amber-colored non-aqueous silver nanoparticle-containing compositionwas obtained and slowly cooled (over 30 minutes) to room temperature.The resulting amount of silver nanoparticles was 33 weight % withrespect to the weight of the cellulose acetate propionate, and theconversion of reducible silver ions to silver nanoparticles wasdetermined to be 97.7 mol % using Capillary Electrophoresis.

An aliquot of this amber-colored non-aqueous silvernanoparticle-containing composition was placed in a 0.1 cm cuvette and aUV-Vis absorption spectrum was recorded, showing a clear plasmonic bandat 440 nm due to the presence of silver nanoparticles in thecomposition. An absorption spectrum of another sample after 1 week ofstorage at ambient conditions showed the same plasmonic band at 440 nm(see FIG. 5) indicating stability of the non-aqueous silvernanoparticle-containing composition. The Tan δ of the non-aqueous silvernanoparticle-containing composition was determined to be 76.1 using theprocess and equipment described above in Invention Example 1.

Invention Example 4: Flexographic Printing and Copper ElectrolessPlating of Non-Aqueous Silver Nanoparticle-Containing Composition on aTransparent Polymeric Substrate

To a sample of the non-aqueous silver nanoparticle-containingcomposition described in Invention Example 3, 10 weight % of propylenecarbonate was added and the resulting composition was mixed thoroughly.Fine lines of nominal width 7-10 μm were printed on a transparentpoly(ethylene terephthalate) film substrate using this composition asthe “ink,” a flexographic test printer IGT F1, and flexographic printingmembers obtained from commercially available Kodak Flexcel NXphotopolymer plates that had been imaged using a mask that was writtenusing the Kodak Square Spot laser technology at a resolution of 12,800dpi.

The “printed” corresponding silver nanoparticle-containing pattern wasdried in air to remove organic solvents. The nominal height of printedfeatures was between 100 nm and 200 nm and the width of resulting finelines was about 5-10 μm.

The resulting precursor article having a pattern of dried non-aqueoussilver nanoparticle-containing composition was immersed in anelectroless copper plating bath, ENTHONE® (Enplate LDS CU-406 SC) at 45°C. for 5 minutes using conditions provided by the commercial supplier.The resulting product article was taken out of the bath, rinsed withwater, and dried. A pattern of metallic copper was seen on the surfaceof the corresponding silver nanoparticle pattern in each productarticle. An electron photomicrograph of the printed and electrolesslycopper plated product article showed clear printed metallic copperlines. The nominal height of printed and copper plated features wasbetween 600 nm and 1200 nm and width of resulting fine lines was 10-15μm.

Invention Example 5: Preparation of Not-Aqueous SilverNanoparticles-Containing Composition in 2-methoxyethanol

In a three-necked round bottomed flask, cellulose acetate (0.5 grams,Sigma Aldrich, 39.7 weight % acetyl, M_(n)˜50,000 by GPC) was dissolvedin 2-methoxyethanol (10 grams) by stirring at 90° C. for 30 minutes toobtain a 5 weight % solution of cellulose acetate in the notedhydroxylic organic solvent. The solution was cooled to room temperatureand silver lactate-pyridine complex (3.75 grams) (prepared as describedin U.S. Ser. No. 15/213,804, noted above) was added while stirring toprovide reducible silver ions. The resulting non-aqueous silverprecursor composition was heated at 50-70° C. for 10 minutes. A darkamber-colored non-aqueous silver nanoparticle-containing composition wasobtained that was slowly cooled (over 30 minutes) to room temperature.This composition had 33 weight % silver nanoparticles with respect tothe weight of the cellulose acetate polymer.

An aliquot of the amber-colored non-aqueous silvernanoparticle-containing composition was placed in a 0.1 cm cuvette and aUV-Vis absorption spectrum recorded, showing a clear plasmonic band at420 nm due to the presence of silver particles in the composition (seeFIG. 6). Conversion of reducible silver ions to silver nanoparticlesfrom the heating process was determined by Capillary Electrophoresis tobe 98 mol %.

Particle size distribution was measured using a light scattering method(Malvern Instruments Ltd. Zetasizer Nano-ZS (ZEN) Dynamic LightScattering or QELS: Quasi-Elastic Light Scatter), and the medianparticle diameter [Dv (50%)] was determined using a dynamic lightscattering method. The size distribution of silver nanoparticlesparticles was determined to be bimodal with approx. 32 volume % of thesilver nanoparticles at 249 nm and 68 volume % of the silvernanoparticles were at 29 nm (the mean silver nanoparticle size was about100 nm). Upon extended keeping of 10 days at room temperature, thesilver nanoparticle size distribution did not change appreciably.

The Tan δ of the non-aqueous silver nanoparticle composition wasdetermined to be 41.9 using the process and equipment described above inInvention Example 1.

Invention Example 6: Preparation of Non-Aqueous SilverNanoparticle-Containing Composition in 2-Methoxyethanol

In a three-necked round bottomed flask, hydroxypropyl cellulose (2.5grams, Sigma Aldrich, M_(w) of 100,000) was dissolved in2-methoxyethanol (46.25 grams) by stirring at 90° C. for 30 minutes.This solution was cooled to room temperature and silver nitrate (1.25grams) was added while stirring to provide reducible silver ions. Theresulting non-aqueous silver precursor composition was heated at 90-100°C. for 10-20 minutes, followed by slowly cooling (over 30 minutes) toroom temperature.

An aliquot of the noted amber-colored non-aqueous silvernanoparticle-containing composition was placed in a 0.1 cm cuvette and aUV-Vis absorption spectrum recorded, showing a clear plasmonic band at425 nm due to the presence of silver nanoparticles (see FIG. 7).Conversion of the reducible silver ions to silver nanoparticles wasdetermined by Capillary Electrophoresis to be 98 mol %. ZEN ParticleSizing of another aliquot of this example showed a trimodal silvernanoparticle size distribution at 500 nm (77 volume %), 55 nm (21 volume%), and 5400 nm (2 volume %), (see FIG. 8). The amount of silvernanoparticles with respect to the hydroxypropyl cellulose was about 33.3weight %.

Invention Example 7: Flexographic Printing and Copper ElectrolessPlating on a Polymeric Substrate

To the non-aqueous silver nanoparticle-containing composition ofInvention Example 6, benzonitrile was added at 20 weight % of theresulting composition that was then thoroughly mixed.

A pattern of fine lines of nominal width 7-10 μm of this non-aqueoussilver nanoparticle-containing composition were printed on apoly(ethylene terephthalate) film substrate using a flexographic testprinter IGT F1 and flexographic printing members obtained fromcommercially available Kodak Flexcel NX photopolymer plates that hadbeen imaged using a mask that was written using the Kodak Square Spotlaser technology at a resolution of 12,800 dpi.

The “printed” corresponding silver nanoparticle-containing pattern wasdried in air to remove organic solvents, and the dried pattern waselectrolessly plated with a Enthone® copper plating chemistry asdescribed above in Invention Example 4 at 40° C., resulting in a copperplated image or pattern (see FIG. 9).

Invention Example 8: Preparation of Non-Aqueous Silver NanoparticleContaining Composition in 2-Methoxyethanol-Benzonitrile Solvent Mixture

In a 25 ml beaker, cellulose acetate (0.5 grams) was dissolved in2-methoxyethanol (7.4 grams) and benzonitrile (1.85 grams)(2-methoxyethanol:benzonitrile at about 8:2 (w/w)) by stirring at 90° C.for 30 minutes. This organic solvent solution was cooled to roomtemperature and silver nitrate (0.25 grams) was added while stirring toprovide reducible silver ions. The resulting non-aqueous silverprecursor composition was heated at 90-110° C. for 10-20 minutes on ahot plate.

An amber-colored non-aqueous silver nanoparticle-containing compositionwas obtained and slowly cooled (over 30 minutes) to room temperature.The resulting amount of silver nanoparticles was 33 weight % withrespect to the weight of the cellulose acetate propionate, and theconversion of reducible silver ions to silver nanoparticles wasdetermined to be 97 mol % using Capillary Electrophoresis. Formation ofsilver nanoparticles was further confirmed by observation of plasmonicband at 420 nm in absorption spectrum (FIG. 10).

Invention Example 9: Addition of Carbon Black to a Preparation ofNon-Aqueous Silver Nanoparticles-Containing Composition in2-methoxyethanol

To the non-aqueous silver nanoparticle-containing composition (10 grams)of Invention Example 1, Cabot Mogul-L Carbon was added at 25 weight %(0.125 grams) with respect to cellulose acetate present in thecomposition. The carbon black was dispersed within the composition usinga Silverson L4R high sheer mixer with a ⅜ inch (0.95 cm) Mini-micromixing head at 12,000 RPM for greater than 5 minutes.

Following procedures described above in previous Invention Examples 2,4, and 7, fine lines of nominal width of 15 μm were printed as a patternon a supporting surface of a transparent poly(ethylene terephthalate)film substrate using the described carbon black-containing, non-aqueoussilver nanoparticle-containing composition as the “ink”.

The “printed” pattern was dried at room temperature in air and waselectrolessly copper plated using ENTHONE® (Enplate LDS CU-406 SC), at40° C. for less than 5 minutes using conditions suggested by thecommercial supplier. A pattern of metallic copper was seen on thesurface of the corresponding silver nanoparticle pattern in each productarticle. The nominal height of printed and copper plated features wasbetween 500 nm and 600 nm and the width of fine lines was 10-25 μm.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

The invention claimed is:
 1. An article comprising a substrate, andhaving disposed on a supporting surface thereof, a pattern of a drysilver nanoparticle-containing composition comprising: at least 20weight % of one or more (a) polymers, based on the total weight of thepattern, which one or more (a) polymers are selected from one or more ofcellulose acetate, cellulose acetate phthalate, cellulose acetatebutyrate, cellulose acetate propionate, cellulose acetate trimellitate,hydroxypropylmethyl cellulose phthalate, methyl cellulose, ethylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose,hydroxypropylmethyl cellulose, and carboxymethyl cellulose; (d) silvernanoparticles having a mean particle size of at least 25 nm and up toand including 750 nm, that are present in the pattern in an amount of atleast 0.1 weight % and up to and including 400 weight %, based on thetotal weight of the one or more (a) polymers; (e) carbon black in anamount of at least 5 weight % and up to and including 50 weight %, basedon the total weight of the one or more (a) polymers; and less than 5 mol% of (b) reducible silver ions, based on the total molar amount of drysilver in the silver nanoparticle-containing composition.
 2. The articleof claim 1, wherein the (d) silver nanoparticles have a mean particlesize of at least 50 nm and up to and including 300 nm.
 3. The article ofclaim 1, wherein the (d) silver nanoparticles are present in an amountof at least 0.1 weight % and up to and including 5 weight %, based onthe total weight of the one or more (a) polymers.
 4. The article ofclaim 1, wherein the (d) silver nanoparticles are present in an amountof at least 15 weight % and up to and including 200 weight %, based onthe total weight of the one or more (a) polymers.
 5. The article ofclaim 1, wherein the substrate is a continuous flexible polymeric film,a metal foil, or a textile web.
 6. The article of claim 1, wherein thesubstrate is a transparent continuous polymeric film.
 7. The article ofclaim 1, wherein the one or more (a) polymers comprise one or more ofcarboxymethyl cellulose, cellulose acetate butyrate, cellulose acetatepropionate, cellulose acetate, and hydroxypropyl cellulose.
 8. Thearticle of claim 1, wherein the pattern of the dry silvernanoparticle-containing composition comprises a combination of finelines, each fine line having an average dry width of at least 0.1 μm andup to and including 20 μm, which combination of fine lines can bearranged in parallel, crossing at any desired angle, a combinationthereof, or in a random arrangement.
 9. The article of claim 1, whereinthe substrate has a first supporting surface and a second opposingsupporting surface, and one or more patterns of the dry silvernanoparticle-containing composition are disposed on the first supportingsurface, and optionally, one or more patterns of the same or differentdry silver nanoparticle-containing composition is disposed on the secondopposing supporting surface.
 10. The article of claim 1, wherein thesubstrate is a transparent continuous polyester film that has a firstsupporting surface and a second opposing supporting surface, the articlefurther comprising multiple individual patterns formed on the firstsupporting surface which one or more multiple individual patternscomprise the same or different dry silver nanoparticle-containingcompositions, and further comprising multiple opposing patterns formedon the second opposing supporting surface that comprise the same ordifferent dry silver nanoparticle-containing compositions.
 11. Thearticle of claim 10, wherein all of the multiple individual patterns onboth the first supporting surface and the second opposing supportingsurface comprise the same dry silver nanoparticle-containingcomposition, the (d) silver nanoparticles in each individual patternhaving a mean particle size of at least 50 nm and up to and including300 nm, and each of the multiple individual patterns comprising finelines having an average dry width of at least 0.1 μm and up to andincluding 20 μm.
 12. The article of claim 1, wherein the pattern of thedry silver nanoparticle-containing composition further comprises atleast 5 weight % and up to and including 25 weight % of a carbon black,based on the total weight of the one or more (a) polymers.
 13. Thearticle of claim 1, further comprising a pattern of electrolessly platedmetal that is disposed solely on the pattern of the dry silvernanoparticle-containing composition.
 14. The article of claim 13,wherein the substrate is a continuous flexible polymeric film, a metalfoil, or a textile web.
 15. The article of claim 13, wherein thesubstrate is a transparent continuous polymeric film.
 16. The article ofclaim 13, wherein the one or more (a) polymers comprise one or more ofcarboxymethyl cellulose, cellulose acetate butyrate, cellulose acetatepropionate, cellulose acetate, or hydroxypropyl cellulose.
 17. Thearticle of claim 13, wherein the pattern of electrolessly plated metalcomprises a combination of fine lines, each fine line having an averagedry width of at least 0.1 μm and up to and including 20 μm, whichcombination of fine lines can be arranged in parallel, crossing at anydesired angle, or a combination thereof or in a random arrangement. 18.The article of claim 13, wherein the substrate has a first supportingsurface and a second opposing supporting surface, and comprises one ormore patterns of electrolessly plated metal disposed on the firstsupporting surface, and optionally, one or more patterns of electrolessplated metal disposed on the second opposing supporting surface.
 19. Thearticle of claim 13, wherein the substrate is a transparent continuouspolyester film that has a first supporting surface and a second opposingsupporting surface, the article further comprising multiple individualpatterns of electrolessly plated copper formed on the first supportingsurface, and comprising multiple individual patterns of electrolesslyplated copper formed on the second opposing supporting surface.
 20. Thearticle of claim 13, wherein the electrolessly plated metal is copper.